Ternary double-exciplex-based synergetic sensitized fluorescent film, preparation method thereof and OLEDs (organic light emitting diodes) device
By using ternary dual excitation composites to synergize fluorescent films in OLEDs, using materials such as TPDI, PO-T2T and tBuCzDBA to form an efficient excitation composite luminescent layer, and synergistically sensitize the fluorescent dye DBP, the problems of low color purity and poor stability in TADF materials in OLEDs are solved, and OLEDs devices with high color purity and high energy transfer efficiency are achieved.
Patent Information
- Application Number
- CN202510303723.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-06-13
AI Technical Summary
The existing TADF materials have problems with low color purity and poor stability in OLEDs, and low concentration doping leads to incomplete energy transfer, affecting device performance.
The fluorescent film based on ternary dual excitation complex is adopted to form an efficient excitation composite luminescent layer by introducing materials such as TPDI, PO-T2T and tBuCzDBA, and synergistically sensitize the traditional fluorescent dye DBP to improve energy transfer efficiency and color purity.
The high color purity and high energy transfer efficiency of OLEDs are achieved, solving the problems of low device efficiency and insufficient color purity.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of organic light-emitting diodes, and particularly to a ternary exciplex co-sensitized fluorescent thin film, a preparation method thereof, and an OLEDs device. Background Art
[0002] Compared with phosphorescent materials with heavy atom effects and containing high-cost and non-renewable precious metals, thermally activated delayed fluorescence (TADF) materials can utilize 75% of non-radiative triplet excitons generated under electrical excitation conditions through reverse intersystem crossing (RISC), and theoretically can achieve 100% exciton utilization efficiency.
[0003] However, the broad emission band of TADF materials will lead to low color purity of OLEDs, and long-lived triplet excitons will reduce the stability of the device and increase the efficiency roll-off of the device at high current density. Traditional fluorescent dyes with ns-level exciton lifetimes, high photoluminescence quantum yields (PLQYs), low costs, narrow spectral bands, and covering the entire emission spectrum are introduced into TADF materials to overcome the defects of TADF materials in OLEDs and prepare highly efficient and stable fluorescent devices.
[0004] Compared with single-molecule TADF materials, exciplexes obtained by directly physically mixing electron donors and acceptor molecules belong to a type of TADF materials, and usually have relatively simple structures, do not require complex and cumbersome synthesis, have smaller singlet-triplet energy gaps, and more efficient RISC processes. Therefore, TADF-type exciplexes that can also achieve 100% internal quantum efficiency are more promising as sensitizing hosts for traditional fluorescent dyes. In the exciplex-sensitized fluorescence system, traditional fluorescent dopants basically use low-concentration doping of less than 2 wt% to avoid direct recombination of excitons on the dopants and short-range Dexter energy transfer of triplet excitons. However, low-concentration doping will lead to incomplete long-range energy transfer, resulting in the CIE color coordinates of exciplex-sensitized fluorescent OLEDs deviating from those of traditional fluorescent OLEDs, and the color purity of the device will be significantly reduced. Therefore, using high energy transfer efficiency (Ф FET ) and high RISC efficiency (Ф RISC ) of TADF-type exciplexes to sensitize traditional fluorescent dyes is very important for realizing highly efficient and high-color-purity exciplex-sensitized fluorescent devices. Summary of the Invention
[0005] The technical problem solved by the present invention is to provide a ternary exciplex co-sensitized fluorescent thin film. The ternary exciplex co-sensitized fluorescent thin film provided by the present application can enable OLEDs to have high color purity and energy transfer efficiency.
[0006] In view of this, the present application provides a fluorescence thin film based on ternary exciplex cooperative sensitization, including a light-emitting layer, and the raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene, and dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene.
[0007] In some specific embodiments, the mass ratio of 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene is 17:(0.5-2):(0.5-2).
[0008] The present application also provides a method for preparing the fluorescence thin film, including the following steps:
[0009] Dissolve 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene in an organic solution of dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene to obtain an exciplex light-emitting layer solution;
[0010] Prepare the exciplex light-emitting layer solution on the surface of the hole transport layer to obtain a fluorescence thin film.
[0011] In some specific embodiments, the concentration of dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene in the exciplex light-emitting layer solution is 0.3-1.0 mg·mL -1 .
[0012] In some specific embodiments, the concentrations of 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene in the exciplex emitting layer solution are independently 3 to 10 mg·mL -1 .
[0013] In some specific embodiments, the material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate).
[0014] In some specific embodiments, the preparation method of the exciplex emitting layer solution is the spin coating method, and the rotation speed of the spin coating method is 1000 to 3000 rpm, and the time is 30 to 90 s.
[0015] In some specific embodiments, the organic solution is a chloroform solution.
[0016] This application also provides an OLEDs device, including: a substrate, a hole transport layer compounded on the surface of the substrate, a light emitting layer compounded on the surface of the hole transport layer, an electron transport layer compounded on the surface of the light emitting layer, an electron injection layer compounded on the surface of the electron transport layer, and a cathode layer compounded on the surface of the electron transport layer; the preparation raw materials of the light emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene, and dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene.
[0017] In some specific embodiments, the substrate is indium tin oxide, and / or, the hole transport layer is a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) layer, and / or, the electron transport layer is a TmPyPB layer, and / or, the material of the electron injection layer is a LiF layer, and / or, the cathode layer is an Al layer.
[0018] The present application provides a ternary exciplex co-sensitized fluorescent thin film, which includes a light-emitting layer. The raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole (TPDI), 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole (PO-T2T), 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene (tBuCzDBA), and dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene (DBP); among the raw materials for the light-emitting layer provided in the present application, TPDI:PO-T2T:tBuCzDBA with high Ф RISC and high Ф FET is selected as the sensitizer, and DBP is used as the fluorescent dye, resulting in red fluorescent OLEDs with high efficiency and high color purity. The high-energy exciplexes TPDI and PO-T2T improve the upconversion efficiency, endowing the ternary exciplex with high Φ RISC to solve the problem of low device efficiency. The low-energy exciplexes TPDI and PO-T2T provide high energy conversion efficiency and have high Φ FET to solve the problem of incomplete energy transfer. Therefore, the ternary exciplex co-sensitized fluorescent thin film provided in the present application has high color purity and energy transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is a schematic structural diagram of an exciplex-sensitized fluorescent device provided by an embodiment of the present invention;
[0020] Figure 2 is a voltage-current density-luminance curve corresponding to Comparative Examples 2-3 and Example 1 in the preparation method of the exciplex-sensitized fluorescent device provided by an embodiment of the present invention;
[0021] Figure 3 is an electroluminescence spectrum corresponding to Comparative Examples 2-3 and Example 1 in the preparation method of the exciplex-sensitized fluorescent device provided by an embodiment of the present invention;
[0022] Figure 4 is a schematic diagram of the light-emitting mechanism of a ternary exciplex co-sensitized fluorescent dopant corresponding to the preparation method of the exciplex-sensitized fluorescent device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.
[0024] In view of the problems of incomplete color purity and energy transfer in exciplex-sensitized fluorescent OLEDs in the prior art, the present application first provides an exciplex ternary double-exciplex synergistic sensitized fluorescent thin film, which is obtained by introducing an electron donor 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole (TPDI), an electron acceptor 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole (PO-T2T), and an electron acceptor 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene (tBuCzDBA) into the raw materials for preparing the light-emitting layer. The three form double-exciplexes TPDI:PO-T2T and TPDI:tBuCzDBA, which is beneficial to obtaining red fluorescent OLEDs with high efficiency and high color purity. Specifically, the present application provides a ternary double-exciplex synergistic sensitized fluorescent thin film, including a light-emitting layer, and the raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene, and dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene.
[0025] In the ternary double-exciplex synergistic sensitized fluorescent thin film provided by the present application, the mass ratio of the electron donor TPDI to the acceptors PO-T2T and tBuCzDBA is 17:(0.5-2):(0.5-2). Specifically, the mass ratios of TPDI, PO-T2T, and tBuCzDBA are 17:1:0.5, 17:1:2, and 17:1:1. Preferably, the mass ratio of TPDI, PO-T2T, and tBuCzDBA is 17:1:1.
[0026] In the ternary exciplex co-sensitized fluorescent thin film provided by the present application, the ternary exciplex sensitizer composed of the electron donor TPDI, the electron acceptor PO-T2T and tBuCzDBA co-sensitizes the fluorescent dye DBP. The high-energy exciplex TPDI:PO-T2T provides a high upconversion efficiency and is responsible for solving the problem of low device efficiency, while the low-energy exciplex TPDI:tBuCzDBA provides a high energy conversion efficiency and is responsible for solving the problem of incomplete energy transfer. The principle is as Figure 4 shown. Thus, the fluorescent thin film provided by the present application can endow OLEDs with high color purity and high conversion efficiency when used as the light-emitting layer.
[0027] The present application also provides a method for preparing the fluorescent thin film, including the following steps:
[0028] Dissolve the electron donor 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, the electron acceptor 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthrene in an organic solution of dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindenoperylene to obtain an exciplex light-emitting layer solution;
[0029] Prepare the exciplex light-emitting layer solution on the surface of the hole transport layer to obtain the fluorescent thin film.
[0030] During the preparation of the fluorescent thin film, in the exciplex light-emitting layer solution, the concentration of dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindenoperylene (DBP) in the exciplex light-emitting layer solution is 0.3 - 1.0 mg·mL -1 , specifically, the concentration of DBP in the exciplex light-emitting layer solution is 0.4 - 0.8 mg·mL -1 , more specifically, the concentration of DBP in the exciplex light-emitting layer solution is 0.5 mg·mL -1The concentrations of 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole (TPDI), 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole (PO-T2T), and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboraanthracene (tBuCzDBA) in the exciplex emitting layer solution are independently 3 to 10 mg·mL -1 , specifically, the concentrations of the TPDI, the PO-T2T, and the tBuCzDBA in the exciplex emitting layer solution are independently 4 to 8 mg·mL -1 , more specifically, the concentrations of the TPDI, the PO-T2T, and the tBuCzDBA in the exciplex emitting layer solution are independently 5 mg·mL -1 . In the present application, the solvent of the exciplex emitting layer solution is selected from chloroform.
[0031] The hole transport layer serves as the substrate of the fluorescent thin film, and its preparation is carried out according to the methods well-known to those skilled in the art, and no special limitation is imposed in this application. The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate).
[0032] In the present application, the fluorescent thin film can be formed on the surface of the hole transport layer by spin coating. The rotation speed of the spin coating method is 1000 to 3000 rpm. Specifically, the rotation speed of the spin coating method is 2000 to 2500 rpm; the time of the spin coating method is 30 to 90 s. Specifically, the time of the spin coating method is 40 to 60 s.
[0033] Furthermore, the present application also provides an OLEDs device, including: a substrate, a hole transport layer compounded on the surface of the substrate, a light emitting layer compounded on the surface of the hole transport layer, an electron transport layer compounded on the surface of the light emitting layer, an electron injection layer compounded on the surface of the electron transport layer, and a cathode layer compounded on the surface of the electron transport layer; the preparation raw materials of the light emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindolo-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphoryloxy)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl))-2,6-dimethylphenyl-5,10-dihydroboraanthracene, and dibenzo{[f,f′]-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene.
[0034] The structural schematic diagram of the OLEDs device provided by the present application is asFigure 1 Specifically, the substrate is conductive indium tin oxide, the hole transport layer is a poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) layer, the electron transport layer is a TmPyPB layer, the electron injection layer is a LiF layer, and the cathode layer is an Al layer. The preparation method of the OLEDs described in this application is prepared according to a method well known to those skilled in the art, and this application has no particular restrictions on this.
[0035] The present application provides a fluorescent film based on a ternary biexcimer complex cooperative sensitization, including a light-emitting layer, wherein the raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene and dibenzo{[f,f′]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene. The fluorescent film provided by the present application is based on a high Φ FET With high Φ RISC The ternary biexciton complex TPDI:PO-T2T:tBuCzDBA synergistically sensitized the traditional fluorescent dye DBP to obtain a fluorescent film, which is conducive to obtaining efficient and high-color-purity solution-processed deep-red light OLEDs, solving the problem that high efficiency and high color purity cannot be achieved at the same time in biexciton-sensitized fluorescent devices.
[0036] In order to further understand the present invention, the ternary biexcimer complex-based cooperatively sensitized fluorescent film, its preparation method and OLEDs device provided by the present invention are described below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.
[0037] Example 1
[0038] The OLEDs device provided by the present invention includes: an anode is a conductive ITO glass substrate; an anode interface layer is PEDOT:PSS (model: 4083); a light-emitting layer is TPDI:PO-T2T:tBuCzDBA:DBP; an electron transport layer is TmPyPB; an electron injection layer is LiF; and a cathode is metal aluminum (Al).
[0039] The preparation method of OLEDs device is specifically as follows:
[0040] (1) Cleaning of the thin film substrate: Taking ITO conductive glass as an example, the substrate glasses are placed side by side on a polytetrafluoroethylene cleaning rack and then placed in an alkaline cleaning solution for ultrasonic treatment for 20 min. Subsequently, ultrasonic treatment is carried out successively with deionized water, acetone, and isopropanol for 10 min each. Then, it is transferred to an oven and dried at 130 °C for more than 2 h to remove the remaining moisture;
[0041] (2) Preparation of the hole transport layer: The ITO glass sheet is placed in an ultraviolet ozone cleaning instrument for ultraviolet ozone treatment for 40 min. About 0.3 mL of PEDOT:PSS solution is extruded using a 0.45 μm PES aqueous filter membrane to cover the ITO glass sheet. The PEDOT:PSS layer is spin-coated with a tabletop spin coater at a speed of 5000 rpm for 45 s, and then transferred to an oven for annealing at 140 °C for 20 min. The annealed ITO glass sheet with the PEDOT:PSS layer is quickly transferred to a glove box and cooled for 10 min;
[0042] (3) Preparation of the light-emitting layer: The electron donor TPDI and the acceptors (PO-T2T, tBuCzDBA) are dissolved in a dilute DBP chloroform solution with a mass ratio of 17:1:1 at 0.025 mg·mL -1 to prepare a 5 mg·mL -1 solution to obtain a 0.5% DBP-doped exciplex light-emitting layer solution; The solution is heated and stirred at 600 rpm and 60 °C for at least 30 min and then cooled to room temperature. Then, the light-emitting layer solution is spin-coated on the PEDOT:PSS / ITO substrate prepared in step (2) at 2500 rpm for 60 s;
[0043] (4) Preparation of the electron transport layer, electron injection layer, and cathode layer: The ITO / PEDOT:PSS / light-emitting layer substrate is transferred to a vacuum evaporation device. When the chamber pressure is lower than 5×10 -7 Torr, a 60 nm electron transport layer TmPyPB, a 1 nm electron injection layer LiF, and a 100 nm cathode layer Al are successively deposited on the light-emitting layer to prepare OLEDs with a light-emitting area of 14 mm 2 ;
[0044] The prepared OLEDs devices are subjected to performance tests. The current density-voltage and brightness-voltage data are measured in a nitrogen glove box using a Keithley 2400 source meter and a calibrated silicon photodiode. The voltage range is 0 - 9 V, the test step size is 0.2 V, and the scanning rate is 0.2 V / s; The electroluminescence spectrum is recorded with a spectro-radiometer CS2000A; The external quantum efficiency is calculated based on the current density, brightness, and its electroluminescence spectrum on the premise that the light-emitting diode is assumed to be a Lambert source. Its performance parameters are shown in Table 1, and its current density-brightness-voltage characteristic curve and electroluminescence spectrum are respectively asFigure 2 and Figure 3 As shown in Table 1 and Figure 2 and Figure 3 it can be seen that the device prepared in the example is the best device, and its maximum external quantum efficiency (EQE) is 14.0%, and the CIE 4V is (0.64, 0.36).
[0045] (5) Preparation and testing of the light-emitting thin film: Place the quartz wafer in an ultraviolet ozone cleaning instrument for ultraviolet ozone treatment for 20 min, and then transfer it to a nitrogen glove box for standby. Use a spin coater to spin coat the light-emitting layer solution at a spin coating parameter of 2500 rpm, an acceleration of 2500 rpm / s, and a time of 60 s at room temperature to prepare the light-emitting layer thin film.
[0046] Perform PLQY and room-temperature transient PL tests on the prepared light-emitting thin film. PLQY is measured using an integrating sphere on an Ocean Optics TEQ-PL system; the room-temperature transient PL decay curve is measured at the maximum emission wavelength of the exciplex and 550 nm on an Edinburgh FLS980 using an EPLED 300 nm laser as the light source; the test and photophysical analysis results are shown in Table 2.
[0047] Example 2
[0048] The difference from Example 1 is that in step (3), the mass ratio of the electron donor TPDI to the acceptors (PO-T2T, tBuCzDBA) in the double exciplex sensitizer used is 17:1:0.5.
[0049] Example 3
[0050] The difference from Example 1 is that in step (3), the mass ratio of the electron donor TPDI to the acceptors (PO-T2T, tBuCzDBA) in the double exciplex sensitizer used is 17:1:2.
[0051] Comparative Example 1
[0052] The difference from Example 1 is that in step (3), the single exciplex sensitizer TPDI:PO-T2T is used, and the ratio of the electron donor TPDI to the acceptor PO-T2T is 17:1.
[0053] Comparative Example 2
[0054] The difference from Example 1 is that in step (3), the single exciplex sensitizer TPDI:tBuCzDBA is used, and the ratio of the electron donor TPDI to the acceptor tBuCzDBA is 17:1.
[0055] The performance detection of the above examples and comparative examples is the same as that of Example 1.
[0056] Table 1 Performance Parameter Data Sheet of OLEDs Prepared in Examples and Comparative Examples
[0057]
[0058] Note: a Voltage at a brightness of 1 cd m -2 ; b Maximum brightness; c Maximum CE; d Maximum EQE; e CIE chromaticity coordinates at 4V.
[0059] In Table 1, the EQE of the OLEDs prepared in Example 2 max is lower than that of Comparative Example 1 because the energy transfer of the OLEDs prepared in Comparative Example 1 is incomplete. It can be found that their CIEs differ quite a lot. From Figure 3 it can be seen that a part of the EL emission of Comparative Example 1 comes from the luminescence of the exciplex itself. The EQE of the OLEDs prepared in Example 3 max is lower than that of Comparative Example 1 but higher than that of Comparative Example 2. Being lower than Comparative Example 1 is partly due to the luminescence of the exciplex itself as mentioned above, and on the other hand, in TPDI:PO-T2T:tBuCzDBA = 17:1:2, some high-energy TPDI:PO-T2T singlet excitons first transfer energy to the low-energy exciplex TPDI:tBuCzDBA and then upconvert to triplet excitons, while the upconversion efficiency of TPDI:tBuCzDBA is lower than that of TPDI:PO-T2T. Being higher than Comparative Example 2 is due to the high upconversion efficiency of the high upconversion efficiency exciplex TPDI:PO-T2T.
[0060] Table 2 Transient PL Characteristics and PLQYs Data Sheet of Films Prepared in Examples and Comparative Examples at 550 nm
[0061]
[0062] a Exciplex TPDI:PO-T2T (17:1); b Exciplex TPDI:tBuCzDBA (17:1); c Exciplex TPDI:PO-T2T:tBuCzDBA (17:1:1); d τ PF and τ DF are the instantaneous fluorescence lifetime and the delayed fluorescence lifetime, respectively; e Φ T , Φ PF and Φ DF are the total PLQY, the PLQY of the instantaneous fluorescence component, and the PLQY of the delayed fluorescence component, respectively; Energy transfer rate; g Φ FET , Φ RISC and Φ RISC / Φ ISC are respectively energy transfer efficiency, RISC efficiency, and the ratio of RISC efficiency to ISC efficiency.
[0063] In summary, for the ternary exciplex co-sensitized fluorescent thin film described in the present invention, TPDI is selected as the electron donor, PO-T2T and tBuCzDBA are used as electron acceptor 1 and acceptor 2 respectively, and DBP is a traditional red fluorescent dye; by using TPDI:PO-T2T:tBuCzDBA (17:1:1) to co-sensitize DBP, the device efficiency and color purity of solution-processed exciplex-sensitized fluorescent OLEDs are better, superior to those of single exciplex devices doped with 0.5% DBP.
[0064] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
[0065] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A fluorescent film based on a ternary biexciton complex cooperative sensitization, comprising a light-emitting layer, wherein the raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene and dibenzo{[f,f′]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene.
2. The sensitized fluorescent film according to claim 1, characterized in that: The mass ratio of the 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, the 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole and the 5,10-di(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene is 17:(0.5~2):(0.5~2).
3. The method for preparing the fluorescent film according to claim 1, comprising the following steps: Dissolving 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole and 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene in an organic solution of dibenzo{[f,f′]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene to obtain an exciplex light-emitting layer solution; The exciplex luminescent layer solution is prepared on the surface of the hole transport layer to obtain a fluorescent film.
4. The preparation method according to claim 3, characterized in that: The concentration of the dibenzo{[f,f′]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene in the exciplex luminescent layer solution is 0.3 to 1.0 mg·mL -1 .
5. The preparation method according to claim 3, characterized in that: The concentrations of 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole and 5,10-di(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene in the exciplex light-emitting layer solution are independently 3 to 10 mg·mL -1 .
6. The sensitized fluorescent film according to claim 3, characterized in that: The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate).
7. The preparation method according to claim 3, characterized in that: The preparation method of the exciplex luminescent layer solution is a spin coating method, wherein the rotation speed of the spin coating method is 1000 to 3000 rpm and the time is 30 to 90 seconds.
8. The preparation method according to any one of claims 3 to 7, characterized in that: The organic solution is a chloroform solution.
9. An OLEDs device, comprising: A substrate, a hole transport layer composited on the surface of the substrate, a light-emitting layer composited on the surface of the hole transport layer, an electron transport layer composited on the surface of the light-emitting layer, an electron injection layer composited on the surface of the electron transport layer, and a cathode layer composited on the surface of the electron transport layer; the raw materials for preparing the light-emitting layer include: 5,10,15-triphenyl-10,15-dihydro-5H-diindole-[3,2-a:3',2'-c]-carbazole, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 5,10-bis(4-(3,6-di-tert-butyl-9H-carbazole-9-yl))-2,6-dimethylphenyl-5,10-dihydroboranthracene and dibenzo{[f,f']-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1',2',3'-lm]perylene.
10. The OLED device according to claim 9, characterized in that: The substrate is conductive indium tin oxide, and / or the hole transport layer is a poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) layer, and / or the electron transport layer is a TmPyPB layer, and / or the material of the electron injection layer is a LiF layer, and / or the cathode layer is an Al layer.