ESIPT luminescent material with high exciton utilization rate and preparation method and application thereof

Abstract

The application discloses an ESIPT luminescent material with high exciton utilization, a preparation method and application thereof, combines ESIPT properties and thermal activated delayed fluorescence properties, designs and synthesizes an ESIPT material capable of generating a high-energy level triplet excited state to a single excited state reverse intersystem crossing mechanism. The molecular excited state of the material has a significant hybridization of local charge transfer properties, and has a high exciton utilization. Meanwhile, the material has good thermal stability and film forming property, and single molecule yellow light and single molecule white light OLEDs are prepared; the application also dopes a TADF blue light material and the above ESIPT yellow light material as a light emitting layer, and the energy transfer between the two is blocked, the complementary color host-guest light emitting peaks are adjusted by a doping ratio, and a low-cost, repeatable, efficient, EL spectrum stable, color adjustable white light OLED device is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electroluminescent materials, and in particular relates to an ESIPT luminescent material with high exciton utilization rate, a preparation method and an application thereof. Background Art

[0002] New energy, display technology, environmental protection, and energy conservation are attracting widespread attention, and various cost-effective products are becoming increasingly popular. White OLED (Organic Light-Emitting Diode) has attracted increasing attention due to its many advantages and promising prospects. For example, it offers full-color display panels, excellent solid-state active illumination, large luminous area applications, low energy loss, and flexible and ultra-thin panels. WOLED (white OLED) offers even greater advantages as a lighting device. Its light emission is close to natural light, soft, radiation-free, environmentally friendly, and beneficial to eye health. Its surface light source properties eliminate eye shadows and dead spots, and it is easy to dissipate heat and consumes very little energy. This creates strong market demand and immeasurable potential. Furthermore, OLED-based mobile phones and TVs have also attracted widespread attention in recent years. From Samsung to the iPhone, they have captured a significant share of the global market, attracting research and development from both domestic and international companies. Compared to display applications, the lighting sector requires maintaining both device efficiency and stability to meet market demands. Simplifying OLED manufacturing processes and reducing costs are emerging trends driving the OLED industry's development.

[0003] The development of OLEDs has gone through four stages: 1) Fluorescent OLEDs; 2) Phosphorescent OLEDs; 3) Thermally Activated Delayed Fluorescence (TADF) OLEDs; and 4) Thermoexciton Fluorescent OLEDs. Fluorescent OLEDs utilize the transition of singlet excitons to emit light, with an internal quantum efficiency of 25%. Phosphorescent OLEDs utilize singlet and triplet excitons, achieving efficient intersystem crossing from singlet to triplet states through spin-orbit coupling, with an internal quantum efficiency of 100%. Unlike traditional fluorescent materials, TADF OLEDs have a smaller energy gap (ΔEst) and can utilize both singlet and triplet excitons simultaneously, with an internal quantum efficiency far exceeding 25%. "Thermoexciton" materials not only efficiently utilize excitons through reverse intersystem crossing at high energy levels, but also effectively suppress various triplet annihilation processes, making them a new generation of high-efficiency OLED materials.

[0004] Thermally activated delayed fluorescence (TADF) materials are capable of capturing all triplet excitons via reverse intersystem crossing (RISC) from the lowest triplet state (T1) to the lowest singlet state (S1), achieving 100% exciton utilization efficiency (EUE). The small energy difference (ΔEst) between S1 and T1 plays a key role in the RISC process in TADF emitters. In the thermally activated state, due to the small energy difference (ΔEst) between the singlet and triplet states, TADF materials are able to convert triplet excitons to singlet excitons through RISC, which then radiate light in the S1 state. Therefore, OLED devices using TADF materials as emitters can achieve near-100% internal quantum efficiency. In OLEDs, excess carriers exist in the device. At high brightness, these excess carriers interact with excitons, resulting in quenching. In phosphorescent OLEDs, triplet-triplet annihilation (TTA) and triplet-singlet annihilation (TSA) primarily occur. TTA is the process in which triplet excitons annihilate one another in excess, converting two triplet excitons into a singlet state. Due to the inherent limitations of TTA upconversion, TTA materials only achieve a maximum theoretical internal quantum efficiency of 62.5%. Furthermore, due to the inherently large length inherent in their molecular design and the quenching of triplet excitons, efficiency decay is severe. Essentially, both TTA and TADF processes can improve the device's external quantum efficiency (EQE) by converting excitons from the lowest triplet excited state (T1) to the lowest singlet excited state (S1). Experimental results confirm that devices based on TTA and TADF materials can achieve high EQE, breaking through the spin-statistical limitation. Despite achieving high EQE in TTA and TADF materials, low exciton utilization remains a challenge.

[0005] Unlike TTA and TADF materials, materials with "hot exciton" properties can achieve reverse intersystem crossing (hRISC) from high-lying triplet excited states (Tn, n ≥ 2) to the lowest singlet excited state (S1). In theory, hRISC along high energy levels should be a fast process (a few nanoseconds), effectively reducing the loss processes associated with long-lived triplet excitons. This rapid hRISC process enables devices with "hot exciton" materials to achieve high EQE, with minimal efficiency rolloff due to triplet trapping and reduced triplet exciton accumulation at high brightness. In fact, nearly 100% singlet exciton yield has been achieved in "hot exciton" OLEDs, with reduced efficiency rolloff. However, due to relatively low photoluminescence quantum yield (PLQY), the EQE fell short of expectations.

[0006] Notably, "hot exciton" materials can strike a good balance between fully utilizing triplet excitons and minimizing efficiency rolloff, as their rapid RISC process effectively reduces triplet exciton annihilation. Currently, the highest external quantum efficiency (EQE) of blue OLEDs fabricated using the hot exciton mechanism has been reported to reach 11.8%, with negligible efficiency roll-off. To achieve efficient hRISC, it is necessary to suppress the IC process from Tn to T1 while accelerating the RISC process from Tn to S1. Therefore, "hot exciton" materials typically possess a large Tn-T1 energy gap and a small Tn-S1 energy gap; the former suppresses the IC process from Tn to T1, while the latter accelerates the hRISC rate from Tn to S1. Theoretically, if the hRISC rate is high enough, the IC process is completely suppressed, and all high-energy triplet excitons are converted to singlet excitons, achieving 100% exciton utilization efficiency.

[0007] WOLED has great research prospects due to its advantages of full color display panel, excellent active luminescence in solid state, and large luminous area. Usually, the white light emission of WOLED is achieved through incomplete energy transfer between different chromogenic materials. Common energy transfers include Energy transfer and Dexter energy transfer. Among them, Energy transfer occurs when the electron clouds between donor and acceptor molecules overlap, and non-radiative energy transfer occurs between molecules. This is a long-range energy transfer. Dexter energy transfer is a short-range energy transfer Produced through multipolar interaction or electron transfer.

[0008] Excited-state intramolecular proton transfer (ESIPT) occurs when a hydrogen bond forms on the oxygen in the enol form (E, also known as the normal state). The molecule becomes excited (E*), leading to a rapid proton transfer process. The hydrogen bond shifts from O-H to N-H, creating a new keto form (K*), also known as a tautomer. The K* state can relax to its tautomeric ground state (K) via keto emission (tautomerism). The K state then returns to the E state via reverse proton transfer, completing a four-level photocycle (E–E*–K*–K–E). Tautomerism typically exhibits a large Stokes shift due to a unique intramolecular four-level photocycle between the keto and enol tautomers, ensuring minimal spectral overlap. Therefore, ESIPT materials hold promise as ideal objects for effectively blocking energy transfer.

[0009] Yellow OLEDs are widely used in life scenes (such as street lamps), medical treatment, display, lithography and other fields; but the research on single-molecule OLEDs based on yellow materials is currently less, and the efficiency of the obtained devices is often not high; it is very important to develop efficient yellow organic electroluminescent devices. The fluorophore with ESIPT property has the characteristics of double emission of enolic and ketonic forms, which makes the high-energy state exciton be more fully utilized, and is more helpful for the improvement of device efficiency. Therefore, we consider using fluorescent molecules with ESIPT properties to prepare high-efficiency monochromatic devices.

[0010] Generally, although the preparation process of energy transfer type WOLED is simple, it is difficult to obtain stable white light emission due to the fine control of the energy transfer process; and the non-energy transfer type WOLED avoids the accuracy and difficulty in controlling the energy transfer process, so it is easier to obtain stable and reproducible WOLEDs. By using the high-energy "hot exciton" reverse intersystem crossing mechanism, high-efficiency OLED blue light materials are used as high-energy light-emitting units, and high-efficiency ESIPT long-wavelength light-emitting materials are used as low-energy light-emitting units for complementation, and a non-energy transfer type binary complementary color solid-state white light blending light-emitting system is designed, so that the performance of the WOLED device can be greatly improved. Generally, the spectrum of the two light-emitting materials in the non-energy transfer type WOLED does not overlap, and the application intends to select a commercial TADF blue light material for doping based on the PyHBT single-molecule yellow device with "high exciton" characteristics, to prepare a non-energy transfer type white light film, in order to develop a high-efficiency and stable WOLED white light device. The main research ideas are as follows: first, the yellow light material PyHBT is used as a guest material, and two traditional blue light TADF materials are selected as the host to prepare complementary color non-energy transfer type white light doped films, and the characteristics and non-energy transfer properties of the white light doped films are studied; then, two single-emitting layer WOLED devices based on blue light host and yellow light guest are prepared, the device structure is optimized, and the high-efficiency light-emitting mechanism and the spectral stability, reproducibility of the non-energy transfer type WOLED are studied, and finally two high-efficiency cool white and warm white WOLEDs are obtained; finally, the physical mechanism of the non-energy transfer type WOLED with high efficiency, high stability and high reproducibility is studied in depth at the molecular level. SUMMARY

[0011] The technical problem solved: In order to overcome the deficiencies in the prior art, the application proposes an ESIPT light-emitting material with high exciton utilization rate and its preparation method and application, to solve the technical problems of low efficiency, complex manufacturing process and high cost of fluorescent OLED devices in the prior art.

[0012] Technical scheme:

[0013] The ESIPT luminescent material with high exciton utilization efficiency is named 2-(phenylene

[0014] [d]thiazol-2-yl)-4-(pyrene-1-yl)phenol PyHBT, the molecular structure of the compound is as follows:

[0015]

[0016] A method for preparing an ESIPT luminescent material with high exciton utilization efficiency comprises the following steps:

[0017] S1: Preparation of intermediate HBT

[0018]

[0019] S2: Preparation of PyHBT

[0020]

[0021] The present application also discloses the application of an ESIPT luminescent material with high exciton utilization rate in an OLED: the OLED is a single-molecule yellow light high-efficiency OLED device, the single-molecule yellow light OLED device comprises an organic light-emitting layer, the material of the organic light-emitting layer is an ESIPT luminescent material PyHBT with high exciton utilization rate doped with a main material DPEPO; the OLED device is a multi-layer structure stacked up and down, the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the The material of the hole blocking layer is DPEPO; the thickness of the hole blocking layer is 5 nm; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 45 nm-75 nm; the material of the electron injection layer is LiF; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the thickness of the electron injection layer is 1 nm, the mass ratio of DPEPO to the ESIPT luminescent material with high exciton utilization is 0.15-0.30; the thickness of the organic light-emitting layer is 30 nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 30 nm-45 nm.

[0022] As a preferred technical solution of the present application: the OLED is a single-molecule white light high-efficiency OLED device, which includes an organic light-emitting layer, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization and doped with a main TADF blue light material DMAC-DPS; the OLED device is a multi-layer structure stacked up and down, wherein the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the hole blocking layer is The material of the organic light-emitting layer is DPEPO; the thickness of the hole blocking layer is 5 nm; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 50 nm-80 nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1 nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the mass ratio of DMAC-DPS to the ESIPT light-emitting material with high exciton utilization is 0.10-0.25; the thickness of the organic light-emitting layer is 40 nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 30 nm-45 nm.

[0023] As a preferred technical solution of the present application: the OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device includes an organic light-emitting layer, the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate doped with a main TADF blue light material DMAc-MPM; the OLED device is a multi-layer structure stacked up and down, the OLED device comprises a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer from bottom to top; the material of the substrate is glass, and the material of the anode layer is an inorganic material; The material of the electron transport layer is B3PyPB; the thickness of the electron transport layer is 50nm-70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of DMAc-MPM to the ESIPT luminescent material with high exciton utilization is 0.05-0.20; the thickness of the organic light-emitting layer is 20nm-35nm; the material of the hole transport layer is TAPC; the thickness of the hole transport layer is 30nm-50nm.

[0024] As a preferred technical solution of the present application: the OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device includes an organic light-emitting layer, the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization and doped with a main TADF blue light material DMAC-DPS; the OLED device is a multi-layer structure stacked up and down, the OLED device is composed of a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer from bottom to top; the material of the substrate is glass, the anode layer The material is an inorganic material; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of DMAC-DPS to the ESIPT luminescent material with high exciton utilization is 0.20; the thickness of the organic light-emitting layer is 20nm to 40nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 35nm.

[0025] As a preferred technical solution of the present application: the OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device includes an organic light-emitting layer, the organic light-emitting layer is composed of a lower layer composed of a blue light-emitting layer DPEPO and a traditional TADF blue light material DMAC-MPM, and an upper layer composed of a blue light-emitting layer DPEPO and the ESIPT light-emitting material PyHBT with high exciton utilization rate; the OLED device is a multi-layer structure stacked up and down, the OLED device is composed of a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer from bottom to top; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the electron transport layer is B3P yPB; the thickness of the electron transport layer is 70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of the blue light emitting layer DPEPO and the traditional TADF blue light material DMAC-MPM is 0.15; the thickness of the lower organic light-emitting layer is 15nm~30nm; the mass ratio of the blue light-emitting layer DPEPO and the ESIPT light-emitting material PyHBT with high exciton utilization is 0.25; the thickness of the upper organic light-emitting layer is 30nm~45nm; the material of the hole transport layer is TAPC; the thickness of the hole transport layer is 30nm.

[0026] As a preferred technical solution of the present application: the inorganic material is indium tin oxide or indium zinc oxide.

[0027] As a preferred technical solution of the present application: the S1 specific steps are: take a three-necked flask, dry in the 120℃ oven for one night, set up the reaction device on the iron stand, take 40mmol 2-aminothiophenol and 40mmol 5-aminosalicylic acid, add them into 200ml polyphosphoric acid (PPA), then replace the gas three times, then connect the condensing water, heat to 168℃ in the N2 environment, reflux for 6 hours, after the reaction is completed, take out the reaction bottle, cool it down, then dissolve the mixture in 300ml ice water mixture, place it in the ice water bath, then add the prepared saturated sodium hydroxide (NaOH) aqueous solution for neutralization, continuously add the ice water mixture for stirring during the neutralization process to prevent the generation of a large amount of heat during the acid-base neutralization to oxidize the product, a large amount of white precipitate will be precipitated out during this process, when the pH value is adjusted to 6, change to saturated sodium bicarbonate (NaHCO3) aqueous solution, meanwhile, stir, until no CO2 bubbles are generated, place the neutralized solution for standing until the solution is clear, then filter, add the filtered solid into saturated sodium bicarbonate aqueous solution, extract with ethyl acetate three times, dry the combined organic layer with anhydrous sodium sulfate (Na2SO4), then rotary evaporate to obtain the crude product, purify with silica gel column to obtain 3.6g light yellow product, the yield is 87%.

[0028] As a preferred technical solution of the present application: the specific steps of using the reactants of 1-bromopyrene and tributyl borate and the intermediate HBT in S2 to prepare the luminescent material PyHBT are as follows: take a dry flask, add 1-bromopyrene to the reaction bottle, evacuate and fill with nitrogen three times; form a low temperature environment of -78°C in a dry ice acetone bath, add 100ml of steamed tetrahydrofuran as a solvent, cool, slowly add 6ml of butyl lithium dropwise, and vigorously stir to react for 2.0h; then add 2.18g of tributyl borate, react for 30min, slowly raise the temperature to room temperature, and continue to react for 12h; after the reaction is completed, add 24ml of hydrochloric acid for hydrolysis, then extract with 300ml of dichloromethane, combine the organic phases, dry, filter and spin dry; evacuate the product for two hours , remove the high boiling point solvent, add it to a three-necked flask, and wrap it with tin foil to avoid light; add 2.38g HBT, add 0.54g Pd(PPh3)4 catalyst under the condition of turning off the lights, charge and discharge nitrogen three times, insert a nitrogen balloon for protection, and at the same time, blow nitrogen into the prepared solvent for half an hour; inject 60ml into the reaction flask, start the agitator to stir the raw materials evenly, connect condensed water, set the reaction temperature to 90℃, wait until the temperature rises to 90℃, add K2CO3 / KF alkali solution, and react for 48h; after the reaction, extract the organic phase with dichloromethane, combine the organic phases, add anhydrous sodium sulfate, stir and dry for half an hour, filter with a Buchner funnel to obtain a filtrate, and then evaporate it to dryness under reduced pressure; separate and purify by a chromatography column method to obtain 2.56g of a yellow solid with a yield of 53.5%.

[0029] Principle explanation: The present invention studies two traditional TADF blue light materials DMAC-DPS, DMAc-MPM and ESIPT yellow light material PyHBT as host and guest respectively, and dopes them in a single light-emitting layer. Based on the energy transfer blocking proof between host and guest, the different proportions between host and guest components are controlled and optimized to prepare non-energy transfer single-emission layer WOLEDs, and finally obtain a high-efficiency white light device. By completely blocking the energy transfer, the "hot exciton" blue light material and the TADF yellow light material can be independently and efficiently utilized for excitons. Therefore, this type of device has excellent efficiency, stable luminescence spectrum and good repeatability. However, considering that the luminescence properties of different luminescent materials in the device are mostly different in the main body, it is not easy to obtain the best device performance in a single light-emitting layer; the blue light layer and the yellow light layer are prepared separately to obtain a dual-emission layer WOLED, and the efficiency of the device is expected to be further improved. Because the energy transfer process is completely blocked, the blue light emission and the yellow light emission are more independent; at the same time, in the dual-emission layer WOLED, the Dexter energy transfer process is also suppressed due to the increased distance of the emission layer. In order to suppress Energy transfer usually requires the addition of a spacer layer, while non-energy transfer dual-emission-layer white light OLEDs do not require a similar spacer layer. Therefore, they can combine the advantages of independent regulation of different light-emitting layers and simple device preparation to obtain high-efficiency WOLEDs that can be prepared at low cost.

[0030] Beneficial effects:

[0031] 1. The present invention designs and proposes an excited-state proton transfer OLED fluorescent material with high exciton utilization based on high-energy-level reverse intersystem crossing. The ESIPT luminescent material with high exciton utilization of the present invention has suitable molecular energy levels, high luminescence efficiency, and good film-forming properties, and can be used as a high-efficiency OLED guest dopant material.

[0032] 2. In finished organic electroluminescent devices, the ESIPT luminescent material of the present invention enables the preparation of single-molecule white OLED devices with high efficiency, simple preparation, and high reproducibility. Furthermore, by doping the classic TADF blue luminescent material with the aforementioned yellow luminescent material as the luminescent layer, efficient white OLED devices with easily reproducible color coordinates and high temperature can be prepared.

[0033] 3. The high exciton utilization ESIPT material described in the present invention is simple to prepare and inexpensive. The single-molecule yellow light OLED, single-molecule white light OLED and binary complementary color non-energy transfer white light OLED devices all have high device efficiency and high exciton utilization, and the ratio is easy to control and the device repeatability is good.

[0034] 4. The binary complementary white light emitting layer is based on a non-energy transfer system. The emission of the blue light material and the yellow light material will not affect each other. By regulating the doping ratio, the host and guest emission peaks can be controlled, thereby preparing a repeatable, chromaticity-adjustable, multi-color OLED with stable color coordinates and electroluminescence spectra. Therefore, it has high use and promotion value.

[0035] 5. The present invention also provides a reference for other related issues in the same field, and can be expanded and extended based on this, and applied to other related technical solutions in the field of organic electroluminescence, and has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 a) Differential Scanning Calorimetry (DSC) curve of PyHBT in Example 1 of the present application; b) Thermogravimetric Analysis (TGA) curve; c) CV curve; d) UPS curve.

[0037] Figure 2 It is the optimal structural energy level diagram of the single-molecule yellow light device in Example 1 of the present application, unit (eV).

[0038] Figure 3is the PL spectra of PyHBT in toluene (1.0 x 10 -5 mol L -1 ) before and after bubbling nitrogen; the right figure is the fluorescence decay spectra of PyHBT in toluene (1.0 x 10 -5 mol L -1 ) before and after bubbling nitrogen.

[0039] Figure 4 is the mechanism diagram of the single-molecule yellow OLED device based on PyHBT in Example 1 of the present application.

[0040] Figure 5 is the PL spectra of a) DAMC-DPS and PyHBT blending films with different ratios (x = 0, 5, 10, 15, 20, 100%) in Example 1 of the present application; b) the transient fluorescence spectra of DAMC-DPS and PyHBT blending films with different ratios (the detection wavelength is 450 nm); c) the PL spectra of DAMC-MPM and PyHBT blending films with different ratios (x = 0, 5, 10, 15, 20, 100%) in Example 1 of the present application; d) the transient fluorescence spectra of DAMC-MPM and PyHBT blending films with different ratios (the detection wavelength is 460 nm).

[0041] Figure 6 is the excitation spectra of DAMC-DPS (left figure) and DMAc-MPM (right figure) and PyHBT blending films with different ratios (the detection wavelength is 400-500 nm for blue light band and 550-650 nm for yellow light band, respectively) in Example 1 of the present application.

[0042] Figure 7 is the energy level diagram of the WOLED device in Example 1 of the present application, unit (eV): a) S1; b) M1.

[0043] Figure 8 is the mechanism diagram of the white OLED device in Example 1 of the present application.

[0044] Figure 9 is the energy level diagram of the WOLED device in Example 1 of the present application, unit (eV): a) S2; b) M2.

[0045] Figure 10The voltage-current density curves of the single carrier devices in Example 1 of the present application are as follows: a) single hole device: ITO / MoO3(1nm) / mCP(35nm) / DMAC-DPS(30nm) / DPEPO(20nm) / DMAC-DPS(30nm) or DPEPO:HBT-Py(20%20nm) / mCP(35nm) / MoO3(1nm) / Al; b) single electron device: ITO / LiF(1nm) / TPBi(70nm) / DPEPO(5nm) / HBT-Py(5nm) / DMAC-DPS(30nm) / DPEPO(20nm) or DPEPO:HBT-Py(20%20nm) / DMAC-DPS(30nm) / HBT-Py(5nm) / DPEPO(5nm) / TPBi(70nm) / LiF(1nm) / Al.

[0046] Figure 11 The voltage-current density curves of the single carrier devices in Example 1 of the present application are as follows: a) single hole device: ITO / TAPC (30 nm) / TCTA (5 nm) / DPEPO (60 nm) or 15% DMAc–MPM:DPEPO (25 nm) / 25% PyHBT:DPEPO (35 nm) / TCTA (5 nm) / TAPC (30 nm) / Al; b) single electron device: ITO / LiF (0.5 nm) / B3PyPB (70 nm) / DPEPO (60 nm) or 15% DMAc–MPM:DPEPO (25 nm) / 25% PyHBT:DPEPO (35 nm) / B3PyPB (70 nm) / LiF (0.5 nm) / Al.

[0047] Figure 12 The optimal structure of the non-energy transfer WOLED in Example 1 of the present application: spectral repeatability of S2 on the left and M2 on the right (detection voltage 10V).

[0048] Figure 13 The optimal structure of non-energy transfer WOLEDs in Example 1 of this application: spectral repeatability of S2 on the left and M2 on the right (detection voltage 6V). DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] Example 1:

[0051] The name of the ESIPT luminescent material with high exciton utilization is 2-(benzo[d]thiazol-2-yl)-4-(pyrene-1-yl)phenol PyHBT.

[0052] The molecular structure of the compound is as follows:

[0053]

[0054] The preparation method of the ESIPT luminescent material with high exciton utilization rate comprises the following steps:

[0055] S1: preparation of intermediate HBT

[0056] Take a three-necked flask, dry it in a 120°C oven overnight, set up the reaction device on the iron stand, take 2-aminobenzene sulfenol (40 mmol) and 5-amino salicylic acid (40 mmol) and add them to 200 ml of polyphosphoric acid (PPA), then replace the gas three times, then set the reaction temperature, connect the condensate water, heat to 168°C in the N2 environment, and reflux for 6 hours. After the reaction is complete, take out the reaction bottle, cool it, and then dissolve the mixture in 300 ml of an ice water mixture, place it in an ice water bath, then add the prepared saturated sodium hydroxide (NaOH) aqueous solution to it for neutralization, continuously add the ice water mixture for stirring during the neutralization process to prevent the generation of a large amount of heat during the acid-base neutralization to oxidize the product. A large amount of white precipitate will be precipitated during this process. When the neutralization is completed and the pH value is adjusted to 6, saturated sodium bicarbonate (NaHCO3) aqueous solution is added, and stirring is simultaneously performed until no CO2 bubbles are generated. After the neutralized solution is allowed to stand until the solution is clear, the obtained solid is extracted with ethyl acetate three times, the organic layer is combined, dried with anhydrous sodium sulfate (Na2SO4), and then rotary evaporated to obtain the crude product. The crude product is purified by silica gel column chromatography to obtain 3.6 g of a light yellow product with a yield of 87%;

[0057]

[0058] S2: preparation of luminescent material PyHBT using 1-bromopyrene and n-tri-butyl borate as reactants and intermediate HBT

[0059]

[0060] Take a dry flask, add 1-bromopyrene to the reaction bottle, vacuum and fill with nitrogen three times; dry ice acetone bath to form a low temperature environment of -78 ° C, add 100 ml of steamed tetrahydrofuran as a solvent, cool, slowly add 6 ml of butyl lithium dropwise, and vigorously stir to react for 2.0 hours; then add 2.18 g of tributyl borate, react for 30 minutes, slowly raise the temperature to room temperature, and continue to react for 12 hours; after the reaction is completed, add 24 ml of hydrochloric acid to hydrolyze, then extract with 300 ml of dichloromethane, combine the organic phases, dry, filter and dry; vacuum the product for two hours, remove the high boiling point solvent, add it to a three-necked flask, wrap with tin foil to protect from light; add 2.38 gHBT, under the condition of turning off the lights, add 0.54gPd(PPh3)4 catalyst, fill and discharge nitrogen three times, insert a nitrogen balloon for protection, and at the same time, blow nitrogen into the prepared solvent for half an hour; inject 60ml into the reaction flask, start the stirrer to stir the raw materials evenly, connect condensed water, set the reaction temperature to 90℃, wait until the temperature rises to 90℃, add K2CO3 / KF alkali solution, and react for 48h; after the reaction, extract the organic phase with dichloromethane, combine the organic phases, add anhydrous sodium sulfate, stir and dry for half an hour, filter with a Buchner funnel to obtain the filtrate, and then evaporate it to dryness under reduced pressure; separate and purify by chromatography column method to obtain 2.56g of yellow solid with a yield of 53.5%; 1 H NMR (400MHz, CDCl3, ppm): δ8.29–8.17(m,4H),8.13(s,2H),8.10–8.01(m,4H),7.96(sd,J=2Hz,1H),7.90(d,J=8.0Hz,1H ),7.67(dd,J=8.2,2Hz,1H),7.55(td,J=7.2,1.2Hz,1H),7.43(td,J=8.2,1.2Hz,1H),7.32(d,J=8.2Hz,1H),1.52(s,1H). 13 C NMR (100MHz, CDCl3, ppm): δ167.69,157.00,151.67,135.29,134.99,132.59,131.50,131.00,130.67,130.50,130.10,128.78,127.66,127.05 ,126.77,126.16,125.84,125.22,124.96,124.72,124.43,121.52,119 .89,118.30,117.96,116.78,116.77,111.02.MALDI-TOFm / z:427.50[M] + .Anal.calcd for C 29 H 17NOS: C, 83.57%; H, 4.76%; found: C, 83.31%; H, 4.53%.

[0061] Table 1 shows the lifetime of PyHBT in toluene solution in the examples of the present application.

[0062]

[0063] a) The uverage lifetime.

[0064] Table 1

[0065] A single-molecule yellow light high-efficiency OLED device comprises an organic light-emitting layer, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate doped with a main material DPEPO.

[0066] The single-molecule yellow light OLED device is a multi-layer structure stacked up and down, and the single-molecule yellow light OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer.

[0067] The following is a further explanation of the technical solution of the present invention in conjunction with a specific manufacturing process of a single-molecule yellow OLED device. The specific manufacturing process of this embodiment is as follows:

[0068] First, the glass substrate is ultrasonically cleaned four times for 15 minutes each time using anhydrous ethanol, acetone, and ultra-clean water. This operation can effectively remove dust and chemically attached dirt on the surface of the ITO glass. After washing, it is placed in a drying oven for drying (about 2 hours). Secondly, the ITO on the glass substrate is pretreated. Plasma treatment can remove organic attachments on the ITO surface, improve the work function of ITO, and reduce the hole injection barrier. Finally, the device is prepared by vacuum evaporation. Prepare the materials to be used for vacuum evaporation and place them in the cavity in turn. When the vacuum degree reaches 3×10 -3 When the pressure is below 10 Pa, the deposition thickness and rate of the thin film on the substrate are monitored in real time by a crystal oscillator, and the evaporation rate is controlled by controlling the current, and each layer of material is deposited in sequence. The evaporation rate of LiF is 10s / Hz, and the evaporation rate of Al is The evaporation rate of other organic materials is 2 Hz / s.

[0069] The structure of the single-molecule yellow OLED device in this embodiment is ITO / MoO3 (1nm) / mCP (35nm) / DPEPO:PyHBT (25% 40nm) / PyHBT (5nm) / DPEPO (5nm) / TPBi (70nm) / LiF (1nm) / Al (100nm). During the vacuum evaporation process, the pressure is less than 1.0×10 -3 Pa, wherein the compound PyHBT is doped on the host material DPEPO as the light-emitting material of the device.

[0070] The technical solution of the present invention provides multiple drawings to illustrate the technical effects of the present invention.

[0071] Specifically, Figure 1 a The glass transition temperature is 207 ° C, and PyHBT loses only 5% of its Tg at 374 ° C ( Figure 1 b), so the material has good thermal stability. Under high temperature conditions, the material can remain stable, which provides a basis for the next step of application to OLED devices. Figure 1 c and 1d, the HOMO energy level of the material is obtained to be -5.92eV, and the LUMO energy level is obtained to be -2.82eV according to the formula and the film absorption spectrum. It can be found that the band gap is similar to that of most common blue emitters, indicating that the frontier molecular orbital is mainly determined by the enol tautomer emitting at about 430nm. This is consistent with the ESIPT characteristic, that is, ESIPT luminophores are more stable in the enol form in the ground state and more stable in the keto form in the excited state; Figure 2 This is the optimal structural energy level diagram, and the prepared OLED device has the highest efficiency. The maximum CE, PE and EQE are 16.81cd / A, 17.29lm / W and 5.64% respectively. It shows a turn-on voltage of 3.6V and CIE coordinates of (0.475, 0.515). In the PyHBT material, holes are the majority carriers, and the 5nm exciton diffusion layer is on the right, which is conducive to faster electron entry into the recombination zone, resulting in better device efficiency. Figure 3 It can be seen from the figure that the steady-state PL spectrum of the compound always shows obvious emission enhancement after nitrogen (deoxygenation) is introduced. After the air is further introduced, the fluorescence decreases again (e.g. Figure 3 Left). Although the transient emission decay curve apparently shows no significant change, the extended lifetime was verified after data fitting of the PL decay curve ( Figure 3Right figure and Table 1). In air, the average fluorescence lifetime in toluene solution was measured to be 1.38ns, showing a biexponential decay of two lifetime components: 0.78 (95.39%) and 13.83 (4.61%) ns; after bubbling nitrogen, the emission band of PyHBT showed a longer average lifetime of 2.36ns, and the two lifetime components of 0.82ns (93.18%) and 23.47ns (6.82%) were extended. At the same time, the proportion of longer lifetimes also increased slightly. After further bubbling air, the average lifetime was shortened again to 1.44ns, and the two lifetime components dropped to 0.78ns (95.47%) and 5.57ns (4.53%), and the ratio of longer lifetimes decreased slightly. All these results confirm the triplet state participation in emission behavior, that is, PyHBT does not have delayed fluorescence characteristics, and the possibility of TTA or TADF mechanism is ruled out. Figure 4 In order to simulate the dynamic process of molecules in the excited state, this application uses time-varying density functional theory for theoretical calculations. In the lowest singlet state (S1), the energy level of the keto form is much smaller than that of the enol form, with a difference of 0.72eV. Therefore, the enol form tends to transfer to the keto form in the excited state, indicating that the emission of the keto form dominates. So we are concerned about the energy levels of the singlet and triplet states of the keto form. For the keto form, the energy level of the lowest singlet state (S1) is 2.68eV, while the triplet energies (T1, T2, T3 and T4) are 1.38, 2.47, 2.67 and 2.87eV respectively. The energy gap between S1 and T1 is very different, up to 1.30eV. This means that reverse intersystem crossing (RISC) from T1 to S1 is almost impossible to occur, which is the TADF process. The energy levels of S1 and T3 are almost the same, which means that a RISC process can occur from T3 to S1. In addition, the energy gap between T3 and T2 is 0.21eV. According to the energy gap law, the internal conversion (IC) rate from T3 to T2 is lower than the RISC rate from T3 to S1. In order to further study the RISC from triplet to singlet state, the SOC matrix element values ​​were calculated. The calculated and The SOC values ​​of the α-Hydroxy-Lysine Hydrochloride (LH-Hydroxy-Lysine Hydrochloride) were 0.497, 0.787 and 1.106 cm–1 respectively. This indicates a potential RISC process from T4 to S1. Therefore, combined with the effects of energy levels and SOC, the “hot exciton” process is promoted through the hRISC transition from T3 and T4 to S1.

[0072] The present invention also discloses a single-molecule white light OLED device, wherein the single-molecule yellow light OLED device includes an organic light-emitting layer, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization efficiency doped with a main TADF blue light material DMAC-DPS or DMAc-MPM.

[0073] The single-molecule white light OLED device is a multi-layer structure stacked up and down. From bottom to top, the white light OLED device consists of a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer (DMAC-DPS is used as the main material) or a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer (DMAc-MPM is used as the main material).

[0074] The specific manufacturing process of the single molecule white light OLED device is the same as that of the single molecule yellow light OLED device.

[0069] The device structure of the single molecule white light OLED device in this embodiment is S1: ITO / MoO3 (1nm) / mCP (35

[0075] nm) / DMAC-DPS:PyHBT(20%40nm) / PyHBT(5nm) / DPEPO(5nm) / TPBi(70nm) / LiF(1nm) / Al and M1:ITO / TAPC(40nm) / TCTA(5nm) / DMAc–MPM:5%PyHBT(35nm) / B3PyPB(70nm) / LiF(0.5nm) / Al. During the vacuum evaporation process, the pressure was less than 1.0×10 -3 Pa, wherein the compound PyHBT is doped on the host material DMAC-DPS or DMAc–MPM as the light-emitting material of the device.

[0076] The technical solution of the present invention provides multiple drawings to illustrate the technical effects of the present invention.

[0077] like Figure 5 As shown in Figures 5a and 5c, with the increase of the doping ratio of PyHBT in the DMAC-DPS main body, the emission of the yellow peak gradually increases and the emission of the blue peak gradually decreases. At a high doping ratio of PyHBT (20wt%), the yellow emission is still obvious, that is, the two can emit light independently; In addition, the fluorescence decay curve is almost independent of the doping concentration of PyHBT. With the change of the doping ratio, the lifetime of the blue peak and the lifetime of the yellow peak do not change significantly ( Figure 5 b, Figure 5 d, Tables 2 and 3), which shows that whether There is no Dexter energy transfer, and the purity of white light can be controlled by adjusting the doping ratio. Figure 6The excitation spectrum of the mixed film detected at 550-650 nm is more similar to the excitation spectrum of PyHBT than to that of DMAC-DPS or DMAc-MPM, indicating that the emission of the yellow guest material is present. Therefore, the energy transfer between the complementary emitters is effectively blocked, otherwise Dexter or The energy transfer will lead to the shortening of the lifetime of the high-energy component. This provides a theoretical basis for the next step of preparing a white light device.

[0078] Table 2 is the lifetime (450 nm detection) of the DAMC-DPS and PyHBT mixed film with different proportions in the examples of the present application

[0079]

[0080] a) The average lifetime.

[0081] Table 2

[0082] Table 3 is the lifetime (460 nm detection) of the DAMC-MPM and PyHBT mixed film with different proportions in the examples of the present application

[0083]

[0084] a) The average lifetime.

[0085] Table 3

[0086] The maximum EQE and CE of device S1 are 9.69% and 27.38 cd / A, respectively, while the maximum EQE and CE of device M1 are 7.89% and 20.25 cd / A, respectively. The exciton utilization rates of the device are 107% and 114%, respectively, which indicates that sufficient exciton utilization has been achieved in both complementary color light-emitting materials. Figure 7 is a WOLED device energy level diagram. As Figure 8As shown in the figure, for the enol form, the energy gap difference between the singlet energy level S1 of the blue TADF host material and the yellow "high exciton" doped guest material is 0.64eV, while the energy gap difference between the T1 of the blue host and the triplet energy level T4 of the yellow doped guest is 0.61eV, which is also too large, indicating that the energy transfer between the two is blocked. In contrast, for the keto form, the S and T energy levels of the blue TADF host and the yellow doped guest are almost the same, indicating that energy transfer is possible. Previous experimental results also showed that there is no energy transfer between the blue host and the yellow doped guest. Therefore, it is believed that the excitons recombine in the enol form, and the recombined excitons are transferred to the keto form through the "ESIPT" process for emission, that is, the host and guest emit light in a non-energy transfer form, thus obtaining a highly efficient WOLED.

[0087] In addition, the present invention also discloses a chromaticity-tunable white light OLED device, wherein the single-molecule yellow light OLED device includes two organic light-emitting layers, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization efficiency doped with a main TADF blue light material DMAC-DPS or DMAc-MPM.

[0088] The white light OLED device is a multi-layer structure stacked up and down, and the white light OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer (with DMAC-DPS as the main material) or a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer (with DMAc-MPM as the main material).

[0089] The device structures of the single-molecule white light OLED device described in this embodiment are S2: ITO / MoO3 (1nm) / mCP (35nm) / DMAC-DPS (30nm) / DPEPO:PyHBT (20% 40nm) / PyHBT (5nm) / DPEPO (5nm) / TPBi (70nm) / LiF (1nm) / Al; M2: ITO / TAPC (30nm) / TCTA (5nm) / 15% DMAc-MPM:DPEPO (25nm) / 25% PyHBT:DPEPO (35nm) / B3PyPB (70nm) / LiF (0.5nm) / Al.

[0090] Similar to single-emission layer WOLEDs, dual-emission layer WOLEDs show an enhancement of yellow emission with increasing bias voltage. Most importantly, the efficiency roll-off has been greatly reduced, with a peak at 1000 cd / m 2The efficiency roll-off of devices S2 and M2 is reduced by 30% and 13%, respectively, at the same luminance. This can be attributed to the prohibition of T-T annihilation and further broadening of the exciton distribution zone. Compared with the single-emitting layer WOLEDs, the luminous efficiency of the double-emitting layer WOLEDs is improved, and the efficiency roll-off is also optimized, in which the efficiency roll-off of S2 is improved by 30% compared with S1, and the efficiency roll-off of M2 is improved by 13% compared with M1, combined with the energy level diagram of the double-emitting layer WOLEDs (as shown in Figure 9 ), compared with the single-emitting layer WOLEDs, the double-emitting layer WOLEDs are more likely to finely control the transport of two kinds of carriers respectively, and thus the transport of holes and electrons is more balanced, so that the device efficiency is further improved; it is particularly important to note that. Due to the effective blocking of the energy transfer process, the exciton spacer layer is not needed in the double-emitting layer structure WOLEDs of the application. Generally, in the traditional multi-layer WOLED, an exciton spacer layer (usually 3-6 nm) is inserted between different emitting layers to prevent Dexter energy transfer and thus prevent exciton quenching. We also prepared two groups of double-emitting layer WOLEDs single-carrier devices, as shown in Figure 10 and 11 . Devices S2 and M2 show much higher efficiency than their corresponding devices S1 and M1, and the maximum EQEs of S2 and M2 are 11.36% and 14.30%, respectively, and the maximum CEs are 32.28 cd / A and 41.07 cd / A, respectively. At a higher operating voltage of 10 V, S2 and M2 show warm white and cold white light emission, respectively, with CIE coordinates of (0.330, 0.457) and (0.270, 0.472), while at a lower bias, both show a dominant blue emission peak; due to the widening of the exciton recombination zone, more excitons are utilized, so the device efficiency of the double-emitting layer WOLEDs is significantly higher than that of the single-emitting layer device.

[0091] The spectral stability of the double-emitting layer non-energy transfer type WOLEDs device is studied, and the detection voltages are 10 V and 6 V, respectively in Figure 12 and Figure 13 , and the color coordinate drift range is also very small, and the color coordinate drift of S2 is from (0.330, 0.457) to (0.319, 0.445) at 10 V, and the color coordinate drift of M2 is from (0.270, 0.472) to (0.212, 0.447); at 6 V, the color coordinate drift of S2 is from (0.217, 0.406) to (0.195, 0.386), and the color coordinate drift of M2 is from (0.242, 0.465) to (0.231, 0.453), that is, at different voltages, the stability of the electroluminescent spectrum is still very good. Similar to the single-emitting layer device, M2 based on DMAc-MPM shows better color stability.

[0092] The present application designs to propose an organic electroluminescent yellow fluorescent proton transfer material and a yellow light OLED prepared by using the material, and a white light OLED device is prepared by doping the classic TADF blue light material and the above-mentioned yellow light material as a light emitting layer. The yellow fluorescent material described in the present application is simple to prepare and low in price. The single-molecule yellow light OLED and the white light OLED device both have high device efficiency and high molecule utilization rate, and the proportion is easy to control, and the device repeatability is good. The white light OLED non-energy transfer system does not affect the blue light emission and the yellow light emission, so the color coordinates and the electroluminescent spectrum are stable, and have high use and popularization value.

[0093] Based on the special properties of ESIPT, the present application designs and synthesizes an ESIPT luminescent material with high exciton utilization rate, which has good carrier transport efficiency and thermal stability. At the same time, the ESIPT luminescent material molecule level of the present application is suitable, has high luminescent efficiency, and has good film forming property, and can be used as a guest doping material. In the finished product of the organic electroluminescent device, a high-efficiency single-molecule yellow light OLED device and a single-molecule white light device are prepared. In addition, the present application dopes the classic TADF blue light material and the above-mentioned yellow light material as a light emitting layer to prepare a white light OLED device. The ESIPT luminescent material of the present application does not occur energy transfer with the host material, and by controlling the doping proportion, the control of the host-guest light emitting peak can be realized, so that the repeatable colorimetric controllable white light OLED is successfully prepared. The single-molecule OLED and the white light OLED device both have high device efficiency and high exciton utilization rate, and the proportion is easy to control, and the device repeatability is good. The color coordinates and the electroluminescent spectrum are stable, and have high use and popularization value.

[0094] The present application also provides a reference for other related problems in the same field, which can be extended and applied to other related technical solutions in the field of organic electroluminescence, and has very broad application prospect.

[0095] Example 2

[0096] The application of ESIPT luminescent materials with high exciton utilization rate in OLED, wherein the inorganic material is indium tin oxide or indium zinc oxide, the OLED is a single-molecule yellow light high-efficiency OLED device, and the single-molecule yellow light OLED device includes an organic light-emitting layer, wherein the material of the organic light-emitting layer is the ESIPT luminescent material PyHBT with high exciton utilization rate doped with the host material DPEPO; the OLED device is a multi-layer structure stacked up and down, wherein the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, and the material of the anode layer is an inorganic material. material; the material of the hole blocking layer is DPEPO; the thickness of the hole blocking layer is 5 nm; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 45 nm-75 nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1 nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the mass ratio of DPEPO to the ESIPT luminescent material with high exciton utilization is 0.15 to 0.30; the thickness of the organic light-emitting layer is 30 nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 30 nm to 45 nm.

[0097] The OLED is a single-molecule white light high-efficiency OLED device, comprising an organic light-emitting layer, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization efficiency doped with a main TADF blue light material DMAC-DPS; the OLED device is a multi-layer structure stacked up and down, wherein the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the hole blocking layer is DPEPO; The thickness of the hole blocking layer is 5nm; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 50nm-80nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of DMAC-DPS to the ESIPT luminescent material with high exciton utilization is 0.10-0.25; the thickness of the organic light-emitting layer is 40nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 30nm-45nm.

[0098] The OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device comprises an organic light-emitting layer, and the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate and a host TADF blue light material DMAc-MPM; the OLED device is a multi-layer structure stacked from bottom to top, and the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, and the material of the anode layer is an inorganic material; the material of the electron transport layer is B3PyPB; the thickness of the electron transport layer is 50-70 nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5 nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the mass ratio of DMAc-MPM to the ESIPT light-emitting material with high exciton utilization rate is 0.05-0.20; the thickness of the organic light-emitting layer is 20-35 nm; the material of the hole transport layer is TAPC; and the thickness of the hole transport layer is 30-50 nm.

[0099] The OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device comprises an organic light-emitting layer, and the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate and a host TADF blue light material DMAC-DPS; the OLED device is a multi-layer structure stacked from bottom to top, and the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, and the material of the anode layer is an inorganic material; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 70 nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1 nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the mass ratio of DMAC-DPS to the ESIPT light-emitting material with high exciton utilization rate is 0.20; the thickness of the organic light-emitting layer is 20-40 nm; the material of the hole transport layer is mCP; and the thickness of the hole transport layer is 35 nm.

[0100] The OLED is a single-molecule white light high-efficiency OLED device, the single-molecule white light OLED device comprises an organic light-emitting layer, the organic light-emitting layer is composed of a lower layer of a blue light emitting layer DPEPO and a conventional TADF blue light material DMAC-MPM and an upper layer of a blue light emitting layer DPEPO and the ESIPT luminescent material PyHBT with high exciton utilization; the OLED device is a multi-layer structure of upper and lower superposition, the OLED device is in turn from bottom to top a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, a cathode layer; the material of the substrate is glass, the material of the anode layer is inorganic material; the material of the electron transport layer is B3PyPB; the thickness of the electron transport layer is 70 nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5 nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100 nm; the material of the hole injection layer is MoO3; the mass ratio of the blue light emitting layer DPEPO and the conventional TADF blue light material DMAC-MPM is 0.15; the thickness of the lower organic light-emitting layer is 15-30 nm; the mass ratio of the blue light emitting layer DPEPO and the ESIPT luminescent material PyHBT with high exciton utilization is 0.25; the thickness of the upper organic light-emitting layer is 30-45 nm; the material of the hole transport layer is TAPC; the thickness of the hole transport layer is 30 nm.

[0101] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, the description of the specification is only for the sake of clarity, the skilled in the art should regard the specification as a whole, the technical solutions in each example can also be combined appropriately to form other embodiments that can be understood by the skilled in the art.

Claims

1. Application of an ESIPT luminescent material with high exciton utilization in an OLED, characterized by: The OLED is a single-molecule yellow light high-efficiency OLED device or a single-molecule white light high-efficiency OLED device, and the single-molecule yellow light OLED device includes an organic light-emitting layer, and the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate doped with a main material DPEPO; the OLED device is a multi-layer structure stacked up and down, and the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the hole blocking layer is DPEPO; the hole The blocking layer has a thickness of 5 nm; the electron transport layer is made of TPBi; the electron transport layer has a thickness of 45 nm to 75 nm; the electron injection layer is made of LiF; the electron injection layer has a thickness of 1 nm; the cathode layer is made of aluminum; the cathode layer has a thickness of 100 nm; the hole injection layer is made of MoO3; the mass ratio of DPEPO to the ESIPT luminescent material with high exciton utilization is 0.15 to 0.30; the thickness of the organic light-emitting layer is 30 nm; the hole transport layer is made of mCP; the hole transport layer has a thickness of 30 nm to 45 nm; the ESIPT luminescent material with high exciton utilization is named 2-(benzo[d]thiazol-2-yl)-4-(pyrene-1-yl)phenol PyHBT, and the molecular structure of the compound is as follows: .

2. Use of the ESIPT luminescent material with high exciton utilization efficiency according to claim 1 in OLED, characterized in that: The OLED is a single-molecule white light high-efficiency OLED device, comprising an organic light-emitting layer, wherein the material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization efficiency doped with a main TADF blue light material DMAC-DPS; the OLED device is a multi-layer structure stacked up and down, wherein the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the hole blocking layer is DPEPO; The thickness of the hole blocking layer is 5nm; the material of the electron transport layer is TPBi; the thickness of the electron transport layer is 50nm-80nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of DMAc-DPS to the ESIPT luminescent material with high exciton utilization is 0.10-0.25; the thickness of the organic light-emitting layer is 40nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 30nm-45nm.

3. Use of the ESIPT luminescent material with high exciton utilization efficiency according to claim 1 in OLED, characterized in that: The OLED is a single-molecule white light high-efficiency OLED device, which includes an organic light-emitting layer. The material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization rate doped with a main TADF blue light material DMAc-MPM. The OLED device is a multi-layer structure stacked up and down. The OLED device comprises a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer from bottom to top. The material of the substrate is glass, and the material of the anode layer is an inorganic material. The material of the electron transport layer is B3PyPB; the thickness of the electron transport layer is 50nm-70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the mass ratio of DMAc-MPM to the ESIPT luminescent material with high exciton utilization is 0.05-0.20; the thickness of the organic light-emitting layer is 20nm-35nm; the material of the hole transport layer is TAPC; the thickness of the hole transport layer is 30nm-50nm.

4. Use of the ESIPT luminescent material with high exciton utilization efficiency according to claim 1 in OLED, characterized in that: The OLED is a single-molecule white light high-efficiency OLED device, which includes an organic light-emitting layer. The material of the organic light-emitting layer is an ESIPT light-emitting material PyHBT with high exciton utilization and a doped TADF blue light-emitting material DMAC-DPS. The OLED device is a multi-layer structure stacked up and down. The OLED device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer. The substrate is made of glass, and the anode layer is made of an inorganic material. ; The material of the electron transport layer is TPBi; the thickness of the electron transport layer is 70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 1nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the material of the hole injection layer is MoO3; the mass ratio of DMAc-DPS to the ESIPT luminescent material with high exciton utilization is 0.20; the thickness of the organic light-emitting layer is 20nm~40nm; the material of the hole transport layer is mCP; the thickness of the hole transport layer is 35nm.

5. Use of the ESIPT luminescent material with high exciton utilization efficiency according to claim 1 in OLED, characterized in that: The OLED is a single-molecule white light high-efficiency OLED device, which includes an organic light-emitting layer, wherein the organic light-emitting layer is composed of a lower layer composed of a blue light-emitting layer DPEPO and a traditional TADF blue light material DMAC-MPM, and an upper layer composed of a blue light-emitting layer DPEPO and the ESIPT light-emitting material PyHBT with high exciton utilization rate; the OLED device is a multi-layer structure stacked up and down, and the OLED device comprises, from bottom to top, a substrate, an anode layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode layer; the material of the substrate is glass, the material of the anode layer is an inorganic material; the material of the electron transport layer is B3P yPB; the thickness of the electron transport layer is 70nm; the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.5nm; the material of the cathode layer is aluminum; the thickness of the cathode layer is 100nm; the mass ratio of the blue light emitting layer DPEPO and the traditional TADF blue light material DMAC-MPM is 0.15; the thickness of the lower organic light-emitting layer is 15nm~30nm; the mass ratio of the blue light-emitting layer DPEPO and the ESIPT light-emitting material PyHBT with high exciton utilization is 0.25; the thickness of the upper organic light-emitting layer is 30nm~45nm; the material of the hole transport layer is TAPC; the thickness of the hole transport layer is 30nm.

6. Use of the ESIPT luminescent material with high exciton utilization efficiency in OLED according to any one of claims 1 to 5, characterized in that: The inorganic material is indium tin oxide or indium zinc oxide.

7. Use of the ESIPT luminescent material with high exciton utilization efficiency in OLED according to any one of claims 1 to 5, characterized in that: The method for preparing the ESIPT luminescent material with high exciton utilization rate comprises the following steps: S1: Preparation of intermediate HBT ； S2: Preparation of PyHBT 。 8. Use of the ESIPT luminescent material with high exciton utilization rate in OLED according to claim 7, characterized in that: The specific steps of S1 are as follows: take a three-necked flask, dry it in an oven at 120°C overnight, set up a reaction device with an iron stand, take 40 mmol of 2-aminobenzenethiol and 40 mmol of 5-aminosalicylic acid and add them to 200 ml of polyphosphoric acid PPA, then ventilate three times, then connect condensed water, heat to 168°C in an N2 environment, reflux for 6 hours, and after the reaction is complete, lift the reaction flask, cool it, and dissolve the mixture in 300 ml ice-water mixture, placed in an ice-water bath, and then added thereto a saturated aqueous sodium hydroxide solution NaOH for neutralization. During the neutralization process, the ice-water mixture was continuously added and stirred to prevent the acid-base neutralization from generating a large amount of heat that would oxidize the product. During this process, a large amount of white precipitate would precipitate. When the pH value was adjusted to 6, a saturated aqueous sodium bicarbonate solution NaHCO3 was added instead, and stirred at the same time until no more CO2 bubbles were generated. The neutralized solution was allowed to stand until the solution clarified and then filtered. The filtered solid was added to a saturated aqueous sodium bicarbonate solution and extracted three times with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate Na2SO4, and evaporated to obtain a crude product, which was purified by silica gel column to obtain 3.6 g of light yellow product with a yield of 87%.

9. Use of the ESIPT luminescent material with high exciton utilization rate in OLED according to claim 7, characterized in that: The specific steps of using the reactants of 1-bromopyrene and tributyl borate and the intermediate HBT to prepare the luminescent material PyHBT in S2 are as follows: take a dry flask, add 1-bromopyrene to the reaction bottle, vacuum and fill with nitrogen three times; form a low temperature environment of -78°C in a dry ice acetone bath, add 100 ml of steamed tetrahydrofuran as a solvent, cool, slowly add 6 ml of butyl lithium dropwise, and vigorously stir to react for 2.0 h; then add 2.18 g of tributyl borate, react for 30 min, slowly raise the temperature to room temperature, and continue to react for 12 h; after the reaction is completed, add 24 ml of hydrochloric acid to hydrolyze, then extract with 300 ml of dichloromethane, combine the organic phases, dry, filter and dry; vacuum the product for two hours to remove the high boiling point solvent, add it to a three-necked flask, wrap it with tin foil to protect it from light; add 2.38 g of HBT, turn off the lights, add 0.54 gPd(PPh3)4 catalyst, fill and discharge nitrogen three times, insert a nitrogen balloon for protection, and at the same time, bubble nitrogen into the prepared solvent for half an hour; inject 60 ml into the reaction flask, start the stirrer to stir the raw materials evenly, connect condensed water, set the reaction temperature to 90℃, wait until the temperature rises to 90℃, add K2CO3 / KF alkali solution, and react for 48 hours; after the reaction, extract the organic phase with dichloromethane, combine the organic phases, add anhydrous sodium sulfate, stir and dry for half an hour, filter with a Buchner funnel to obtain the filtrate, and then evaporate it to dryness under reduced pressure; separate and purify it by chromatography column method to obtain 2.56 g of yellow solid with a yield of 53.5%.

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