阅读说明：本技术 一种有机黄色荧光激发态质子转移材料及其oled器件 (Organic yellow fluorescence excited state proton transfer material and OLED device thereof ) 是由 钱妍 臧璇 密保秀 高志强 于 2021-05-20 设计创作，主要内容包括：本申请公开了一种基于高能级反向系间窜越的高效有机黄色荧光激发态质子转移材料及其OLED器件,并将经典TADF蓝光材料与上述黄光材料掺杂作为发光层,制备白光OLED器件。本发明所述的黄色荧光激发态质子转移材料制备简单,价格低廉,所述的单分子黄光OLED以及白光OLED器件都具备较高的器件效率以及较高的激子利用率,并且比例容易调控,器件可重复性好。其中白光发光层基于非能量传递体系,蓝光材料发射与黄光材料发射不会相互影响,因此色坐标与电致发光光谱稳定,具有很高的使用及推广价值。(The application discloses a high-efficiency organic yellow fluorescence excited state proton transfer material based on high-energy-level reverse intersystem crossing and an OLED device thereof, and a classic TADF blue light material and the yellow light material are doped to be used as a light emitting layer to prepare a white light OLED device. The yellow fluorescence excited state proton transfer material is simple to prepare and low in price, and the monomolecular yellow light OLED and the white light OLED have high device efficiency and high exciton utilization rate, the proportion is easy to regulate and control, and the device repeatability is good. The white light emitting layer is based on a non-energy transfer system, and blue light material emission and yellow light material emission cannot be influenced mutually, so that the color coordinate and the electroluminescence spectrum are stable, and the white light emitting layer has high use and popularization values.)

1. An organic yellow fluorescence excited state proton transfer material, which is characterized in that: the name of the organic yellow fluorescence excited-state proton transfer material is 2- (benzothiazole-2-yl) -4- (phenanthrene-9-yl) phenol, and the structural formula is as follows:

2. a monomolecular yellow OLED device is characterized in that: the single-molecule yellow OLED device comprises an organic light-emitting layer, wherein the organic light-emitting layer is made of an organic yellow fluorescence excited-state proton transfer material and a main material mCP (metal doped phosphor).

3. The single-molecule yellow OLED device of claim 2, wherein: the single-molecule yellow-light OLED device is of a multi-layer structure which is overlapped up and down, and sequentially comprises 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 from bottom to top.

4. A monomolecular yellow light OLED device with an exciton diffusion layer is characterized in that: the monomolecular yellow light OLED device with the exciton diffusion layer comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is made of an organic yellow fluorescence excited state proton transfer material and a main material mCP (metal-doped phosphorus) which are doped, and the exciton diffusion layer is made of an organic yellow fluorescence excited state proton transfer material.

5. A white OLED device characterized by: the white OLED device comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is doped by the organic yellow fluorescence excitation state proton transfer material and a classic high-efficiency blue light TADF material DMAC-DPS according to claim 1, and the exciton diffusion layer is the organic yellow fluorescence excitation state proton transfer material according to claim 1.

6. OLED device according to claim 4 or 5, characterized in that: the monomolecular yellow light OLED device or the white light OLED device with the exciton diffusion layer is of a multi-layer structure which is overlapped up and down, and the white light OLED device sequentially comprises a substrate, an anode layer, a hole injection layer, a hole transmission layer, an organic light emitting layer, the exciton diffusion layer, a hole blocking layer, an electron transmission layer, an electron injection layer and a cathode layer from bottom to top.

7. An OLED device according to any one of claims 2-5, wherein: the substrate is made of glass or flexible plastic.

8. An OLED device according to any one of claims 2-5, wherein: the anode layer is made of an inorganic material, and the inorganic material is indium tin oxide or indium zinc oxide.

9. An OLED device according to any one of claims 2-5, wherein: the hole injection layer is made of MoO₃(ii) a The thickness of the hole injection layer is 0.8nm-1.5nm, and the material of the hole transport layer is mCP; the thickness of the hole transport layer is 10nm-50nm, the thickness of the organic light-emitting layer is 20nm-50nm, and the material of the hole blocking layer is DPEPO; the thickness of the hole blocking layer is 2nm-10nm, and the material of the electron transport layer is TPBI; the thickness of the electron transport layer is 10nm-50nm, and the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.8nm-1.5nm, and the cathode layer is made of any one of gold, silver, copper, aluminum and magnesium; the thickness of the cathode layer is 100nm-200 nm.

10. OLED device according to claim 4 or 5, characterized in that: the exciton diffusion layer has a thickness of 2nm to 10 nm.

Technical Field

The invention belongs to the technical field of organic electroluminescent materials, and particularly relates to an organic yellow fluorescence excited state proton transfer material and an OLED device thereof.

Background

The organic light-emitting material is the core technology of the organic electroluminescent device and is also the focus of international competition in the field. The first generation of OLED luminescent materials are fluorescent materials with an internal quantum efficiency limit of 25%. However, due to spin statistical limitations, fluorescent materials can only emit with 25% of Singlet (S) excitons, while 75% of Triplet (T) excitons are wasted. The second generation of OLED luminescent materials are metal complex phosphorescent materials mainly represented by iridium complexes, platinum complexes and the like. The spin-orbit coupling is greatly enhanced by utilizing the heavy atom effect in the metal complex, so that the spin forbidden transition between the original S excited state and the original T excited state is converted into the spin allowed transition. Therefore, 100% complete utilization of S-state and T-state excitons can be realized, and the internal quantum efficiency can theoretically reach 100%. However, noble metals (such as iridium, platinum, etc.) are scarce and expensive, which also greatly limits the further development and application of phosphorescent OLED materials. The third generation of OLED materials is a Delayed Fluorescence material that utilizes the conversion of T-state excitons into S-state excitons for light emission, and includes Triplet-Triplet annihilation (TTA) materials and Thermally Activated Delayed Fluorescence (TADF) materials. However, the TTA process is such that two lowest triplet (T1) excitons are converted into one radiation-transition lowest singlet (S1) exciton and one ground state singlet (S0) exciton by collision annihilation, and half of the triplet excitons are still wasted in this process, i.e. the maximum exciton utilization rate can only reach 62.5%. Most TADF materials have Charge Transfer (CT) excited states with spatially separated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO), and this spatial separation of Charge distribution results in poor electron exchange and thus energy level splitting Δ E between S1-T1 states_STVery small and thus Reverse Intersystem Crossing (RISC) from T1 to S1 is easily achieved under thermally activated conditions. However, the CT excited state generally results in a reduction in emission efficiency due to space charge separation of HOMO and LUMO orbitals. In addition, long lifetime T is accumulated in the electroluminescent device due to the generally slow rate of intersystem crossing1 excitons are susceptible to triplet-triplet exciton annihilation (TTA), triplet-singlet exciton annihilation (TSA), or triplet exciton-polaron annihilation (TPA), which results in electroluminescent devices employing TTA or TADF materials (even when doped) typically having severe roll-off efficiency at high current densities. Therefore, the development of a new generation of OLED materials with low cost, high light-emitting efficiency, high exciton utilization rate, and good stability is imminent.

In recent years, faster triplet exciton kinetics at higher energy levels have attracted increasing attention. By introducing rapid RISC from the high-energy triplet excited state to the singlet excited state while suppressing Internal Conversion (IC) between the high-energy triplet excited state and the low-energy triplet excited state, exciton utilization efficiency limited by spin-forbidden resistance of conventional fluorescent materials can also be broken through, thereby hopefully realizing a singlet exciton yield of nearly 100%, which is also referred to as a "hot exciton" mechanism. More importantly, the rapid RISC between high-level excited states can effectively reduce the increase of triplet exciton concentration caused by the increase of current density, thereby inhibiting the annihilation effect of TTA, TSA, TPA and the like and the efficiency roll-off of the OLED device caused by the annihilation effect.

As an ideal light source, the light-emitting band of WOLED should cover the whole visible light region (400-800nm) and have continuous spectrum, but the light-emitting range of most organic light-emitting materials is limited to a narrow light-emitting band, and only a single light-emitting color can be presented. The WOLED structure is more complicated because different lights need to be mixed to obtain white light. The means for preparing the WOLED mainly comprise a doped single light-emitting layer structure, a multiple light-emitting layer structure, a series structure, a parallel structure and the like. The structure of the multiple light-emitting layers has the defect of complex preparation process, while the structure of the doped single light-emitting layer has relatively simple preparation process, but the energy transfer between the two light-emitting components is difficult to accurately control. The degree of energy transfer can affect the luminescence of the different components, and the stability of the different components can also affect the color purity of the device. Therefore, it is a difficult problem for researchers to control the energy transfer between the components accurately and make the components emit light without interference. Compared with a general organic light emitting compound, an Excited State Intramolecular Proton Transfer (ESIPT) compound can effectively avoid spectral overlap between a host and a guest material due to its large Stokes shift, and thus it is highly likely to block energy Transfer between host and guest molecules. If the ESIPT compound is used as a long-wavelength energy acceptor of low-energy luminescence and then an appropriate energy-matched short-wavelength energy donor of high-energy luminescence is selected, the spectral overlap is very small, so that energy transfer is difficult between the ESIPT compound and the short-wavelength energy donor, and independent luminescence without influence of different luminescent components is realized.

Based on the above discussion, we assume that if a material with "thermal exciton" RISC properties is introduced into a non-energy transfer system, then a high performance WOLED with low cost, high efficiency, stability, simple preparation, good repeatability.

Disclosure of Invention

The technical problem to be solved is as follows: in order to overcome the defects in the prior art, the application provides an organic yellow fluorescence excited-state proton transfer material and an OLED device thereof, and aims to solve the technical problems that precious metal resources are scarce, the price is high, the efficiency roll-off is serious under high current density and the like in the prior art.

The technical scheme is as follows:

an organic yellow fluorescence excitation state proton transfer material is named as 2- (benzothiazole-2-yl) -4- (phenanthrene-9-yl) phenol, and the structural formula is as follows:

a single-molecule yellow OLED device comprises an organic light-emitting layer, wherein the organic light-emitting layer is made of the organic yellow fluorescence excited-state proton transfer material and the host material mCP in a doped mode.

As a preferred technical scheme of the application: the single-molecule yellow-light OLED device is of a multi-layer structure which is overlapped up and down, and sequentially comprises 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 from bottom to top.

The monomolecular yellow-light OLED device with the exciton diffusion layer comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is made of an organic yellow fluorescence excited state proton transfer material and a main material mCP (metal organic phosphorus) in a doped mode, and the exciton diffusion layer is made of an organic yellow fluorescence excited state proton transfer material.

A white OLED device comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is made of the organic yellow fluorescence excited state proton transfer material and is doped with a classic high-efficiency blue light TADF material DMAC-DPS, and the exciton diffusion layer is made of the organic yellow fluorescence excited state proton transfer material.

As a preferred technical scheme of the application: the monomolecular yellow light OLED device or the white light OLED device with the exciton diffusion layer is of a multi-layer structure which is overlapped up and down, and the white light OLED device sequentially comprises a substrate, an anode layer, a hole injection layer, a hole transmission layer, an organic light emitting layer, the exciton diffusion layer, a hole blocking layer, an electron transmission layer, an electron injection layer and a cathode layer from bottom to top.

As a preferred technical scheme of the application: the substrate is made of glass or flexible plastic.

As a preferred technical scheme of the application: the anode layer is made of an inorganic material, and the inorganic material is indium tin oxide or indium zinc oxide.

As a preferred technical scheme of the application: the material of the hole injection layer is MoO₃(ii) a The thickness of the hole injection layer is 0.8nm-1.5nm, and the material of the hole transport layer is mCP; the thickness of the hole transport layer is 10nm-50nm, the thickness of the organic light-emitting layer is 20nm-50nm, and the material of the hole blocking layer is DPEPO; the thickness of the hole blocking layer is 2nm-10nm, and the material of the electron transmission layerThe material is TPBI; the thickness of the electron transport layer is 10nm-50nm, and the material of the electron injection layer is LiF; the thickness of the electron injection layer is 0.8nm-1.5nm, and the cathode layer is made of any one of gold, silver, copper, aluminum and magnesium; the thickness of the cathode layer is 100nm-200 nm.

As a preferred technical scheme of the application: the exciton diffusion layer has a thickness of 2nm to 10 nm.

Has the advantages that:

1. the invention provides a high-efficiency organic yellow fluorescence excited state proton transfer material based on high-energy-level reverse intersystem crossing, and a classic TADF blue light material and the yellow light material are doped to be used as a light emitting layer to prepare a white light OLED device. The yellow fluorescence excited state proton transfer material is simple to prepare and low in price.

2. The invention also provides reference for other related problems in the same field, can be expanded and extended based on the mechanism, is applied to other related technical schemes in the field of organic electroluminescence, and has very wide application prospect.

3. The monomolecular yellow light OLED and the white light OLED both have high device efficiency and high exciton utilization rate, the current efficiency, the power efficiency and the external quantum efficiency of the monomolecular yellow light device are respectively 5.90cd/A, 5.37lm/W and 4.014%, the current efficiency, the power efficiency and the external quantum efficiency of the white light OLED are respectively 16.837cd/A, 11.287lm/W and 13.565%, the proportion is easy to regulate and control, and the device repeatability is good.

4. The white light emitting layer is based on a non-energy transfer system, and blue light material emission and yellow light material emission cannot be influenced mutually, so that the color coordinate and the electroluminescence spectrum are stable, and the white light emitting layer has high use and popularization values.

Drawings

FIG. 1 is a diagram of a single-molecule yellow OLED device according to an embodiment of the present application.

FIG. 2 is a graph of the electroluminescence spectrum of a single-molecule yellow OLED device in the example of the present application.

Fig. 3 is a graph of current density-voltage-luminance for a single-molecule yellow OLED device in accordance with an embodiment of the present application.

Fig. 4 is a graph of current efficiency-luminance-power efficiency for a single-molecule yellow OLED device in accordance with an embodiment of the present application.

FIG. 5 is a graph of luminance versus external quantum efficiency for a single-molecule yellow OLED device in accordance with an example of the present application.

Fig. 6 is a molecular energy diagram of a yellow light material according to an embodiment of the present application.

FIG. 7 is a diagram of the structure of a monomolecular yellow OLED device incorporating an exciton diffusion layer according to example two of this application.

FIG. 8 is a graph of the electroluminescence spectrum of a monomolecular yellow OLED device incorporating an exciton diffusion layer in example two of this application.

FIG. 9 is a graph of current density-voltage-luminance for a single-molecule yellow OLED device incorporating an exciton diffusion layer in example two of the present application.

FIG. 10 is a graph of current efficiency-luminance-power efficiency for a single molecule yellow OLED device incorporating an exciton diffusion layer in example two of the present application.

FIG. 11 is a graph of luminance versus external quantum efficiency for a single molecule yellow OLED device incorporating an exciton diffusion layer in example two of the present application.

Fig. 12 is a device structure diagram of a white OLED device in the third embodiment of the present application.

FIG. 13 is a graph of the electroluminescence spectrum of a white OLED device in example III of the present application.

FIG. 14 is a graph of current density-voltage-luminance of a white OLED device in example three of the present application.

FIG. 15 is a graph of current efficiency-luminance-power efficiency of a white OLED device in example three of the present application.

Fig. 16 is a graph of luminance versus external quantum efficiency for a white OLED device in example three of the present application.

FIG. 17 shows an emission spectrum of a blue material and an absorption spectrum of a yellow material in example III of the present application.

Detailed Description

The application discloses an organic yellow fluorescence excited state proton transfer material, which is named as 2- (benzothiazole-2-yl) -4- (phenanthrene-9-yl) phenol (HBT-PA) and has the following structural formula:

the preparation process of the organic yellow fluorescence excited state proton transfer material mainly comprises the following steps:

bromophenyl (0.26g, 1mmol) and 2- (benzothiazol-2-yl) -4- (4,4,5, 5-tetramethyl-1, 3, 2-dioxolan-2-yl) phenol (HBT-4PD) (0.42g, 1.2mmol) were combined in a 50ml flask and weighed to add 4,3 phenylphosphine palladium (115mg, 0.1mmol), the apparatus was sealed with a rubber stopper and sealing membrane, evacuated using a double calandria, purged with nitrogen three times, and a nitrogen balloon was inserted. 2.5ml of the prepared mixed aqueous solution of 2mol/L potassium carbonate and 2mol/L potassium fluoride was added, and 20ml of a mixed solvent of toluene and tetrahydrofuran at a ratio of 1:1 was added. All solvents and solutions required 30 minutes of nitrogen sparging. The reaction device is put into an oil bath kettle, the liquid level in the bottle is slightly higher than the liquid level of the oil bath kettle, and the heating reflux reaction is carried out for 24 hours at the temperature of 90 ℃. After the reaction is finished, extracting by using water and dichloromethane, collecting lower layer solution, spin-drying, adding silica gel powder, stirring uniformly, using a mixed solvent of petroleum ether and dichloromethane in a ratio of 1:1 as an eluent, spin-drying after column chromatography to obtain a light yellow solid, and recrystallizing by using dichloromethane and methanol solution to obtain a product of about 300mg, wherein the yield is 75%. 1H NMR (400MHz, CDCl3, ppm): δ 8.81(d, J ═ 8.2Hz,1H),8.75(d, J ═ 8.2Hz,1H),8.05(d, J ═ 8.2Hz,1H), 8.00-7.86 (M,4H),7.75(s,1H), 7.74-7.61 (M,3H), 7.60-7.52 (M,3H),7.27(d, J ═ 8.2Hz,1H),1.55(s,1H), 13C NMR (100MHz, CDCl3, ppm δ 169.127, 157.44,151.80,137.53,134.58,132.69,132.17,131.59,131.31,130.82,130.08, ppm:, Δ 169.127, 157.44,151, 137.53,134.58,132.69,132, 132.17,131.59,131.31,130.82,130.08, 65, 77, 59, 23, 27; h, 4.76%; found is C, 83.31%; h,4.53 percent.

The technical solution of the present invention is further described below with reference to the specific process for fabricating the OLED device.

Example 1:

the single-molecule yellow OLED device comprises an organic light-emitting layer, wherein the organic light-emitting layer is made of an organic yellow fluorescence excited-state proton transfer material and a host material mCP in a doping mode.

The single-molecule yellow-light OLED device is of a multi-layer structure which is overlapped up and down, and sequentially comprises 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 from bottom to top.

The specific manufacturing process of this embodiment is as follows:

the first step is as follows: cleaning ITO (indium tin oxide) glass, respectively ultrasonically cleaning the ITO glass with acetone, water and ethanol for 30min, and then drying in an oven for 1 h;

the second step is that: carrying out plasma treatment on the ITO (indium tin oxide) glass dried by the oven for 45 s;

the third step: vacuum evaporation of hole injection layer MoO on anode ITO glass₃The evaporation rate is 2Hz/s, and the thickness of the evaporation film is 0.8nm-1.5 nm;

the fourth step: in the hole injection layer MoO₃Vacuum evaporating a hole transport layer mCP, wherein the evaporation rate is 2Hz/s, and the evaporation film thickness is 10nm-50 nm;

the fifth step: vacuum evaporating organic light-emitting layer mCP (HBT-PA) (3:1) on the hole transport layer at 2Hz/s and 20-60 nm of total film thickness;

and a sixth step: on the organic light-emitting layer, vacuum evaporation plating is carried out on DPEPO serving as a hole blocking layer, the evaporation plating rate is 2Hz/s, and the thickness is 2nm-10 nm;

the seventh step: and (3) vacuum evaporating TPBI serving as an electron transport layer on the hole blocking layer, wherein the evaporation rate is 2Hz/s, and the thickness is 10nm-50 nm:

eighth step: vacuum evaporating LiF as an electron injection layer on the electron transport layer, wherein the evaporation rate is 0.1Hz/s, and the thickness is 0.8nm-1.5 nm;

the ninth step: and vacuum evaporating a cathode layer Al on the electron injection layer, wherein the thickness of the cathode layer Al is 100nm-200 nm.

The device structure of the monomolecular yellow OLED device in the embodiment is ITO/MoO₃HBT-PA/DPEPO/TPBI/LiF/Al, as shown in FIG. 1, the pressure is less than 1.0 × 10-³Pa, wherein the compound 2- (benzothiazol-2-yl) -4- (phenanthrene-9-yl) phenol is used as a luminescent material of the device.

The device is subjected to OLED property test, and the maximum current density of the device is 259.77mA/cm²Maximum luminance of 941.36cd/m²No significant change in the electroluminescence spectrum occurred at any of the five randomly selected voltages. The maximum current efficiency is 3.44cd/A, the maximum power efficiency is 2.70lm/W, and the maximum external quantum efficiency is 1.74%. Measuring the fluorescence quantum efficiency of the device to obtain 21.1% fluorescence quantum efficiency, and obtaining the fluorescence quantum efficiency by a formula eta_r＝EQE_max/(γ×η_PL×η_out) The exciton utilization of the device was calculated to be 41.23%. The HBT-PA molecular energy level diagram is calculated, and energy gaps between T8 and S2, and between T9 and S3 are smaller and are respectively 0.005 eV and 0.07 eV. This indicates the possibility that excitons in the yellow light material ESIPT material molecule have a cross-over transition from a high-energy triplet-reverse intersystem to a singlet state. The results of the experiment are shown in FIGS. 2 to 6.

Example 2:

the monomolecular yellow light OLED device with the exciton diffusion layer comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is made of the organic yellow fluorescence excited state proton transfer material and a host material mCP which are doped, and the exciton diffusion layer is made of the organic yellow fluorescence excited state proton transfer material.

The monomolecular yellow-light OLED device with the exciton diffusion layer is of a multi-layer structure which is overlapped up and down, and the monomolecular yellow-light OLED device sequentially comprises a substrate, an anode layer, a hole injection layer, a hole transmission layer, an organic light emitting layer, the exciton diffusion layer, a hole blocking layer, an electron transmission layer, an electron injection layer and a cathode layer from bottom to top.

The specific manufacturing process of this embodiment is as follows:

the first step is as follows: cleaning ITO (indium tin oxide) glass, respectively ultrasonically cleaning the ITO glass with acetone, water and ethanol for 30min, and then drying in an oven for 1 h;

the second step is that: plasma treatment for 45 s;

the third step: vacuum evaporation of hole injection layer MoO on anode ITO glass₃The evaporation rate is 2Hz/s, and the thickness of the evaporation film is 0.8nm-1.5 nm;

the fourth step: in the hole injection layer MoO₃Vacuum evaporating a hole transport layer mCP, wherein the evaporation rate is 2Hz/s, and the evaporation film thickness is 10nm-50 nm;

the fifth step: vacuum evaporating organic light-emitting layer mCP (HBT-PA) (3:1) on the hole transport layer at 2Hz/s and 20-60 nm of total film thickness;

and a sixth step: on the organic light emitting layer, vacuum evaporation is carried out on HBT-PA used as an exciton diffusion layer, the evaporation rate is 2Hz/s, and the thickness is 2nm-10 nm;

the seventh step: and (2) vacuum evaporating DPEPO as a hole blocking layer on the exciton diffusion layer, wherein the evaporation rate is 2Hz/s, and the thickness is 2nm-10 nm:

eighth step: vacuum evaporating TPBI serving as an electron transport layer on the hole blocking layer, wherein the evaporation rate is 2Hz/s, and the thickness is 10nm-50 nm;

the ninth step: vacuum evaporating LiF as an electron injection layer on the electron transport layer, wherein the evaporation rate is 0.1Hz/s, and the thickness is 0.8nm-1.5 nm;

the tenth step: and vacuum evaporating cathode Al on the electron injection layer to a thickness of 100nm-200 nm.

The device structure of the monomolecular yellow OLED device in the embodiment is ITO/MoO₃The pressure during the vacuum evaporation process is less than 1.0 × 10-³Pa, wherein the compound 2- (benzothiazol-2-yl) -4- (phenanthrene-9-yl) phenol is used as a luminescent material of the device.

The device is subjected to OLED property test, and the maximum current density of the device is 260.69mA/cm²Maximum luminance of 3437.6cd/m²No significant change in the electroluminescence spectrum occurred at any of the five randomly selected voltages. The maximum current efficiency is 5.99cd/A, the maximum power efficiency is 5.37lm/W, and the maximum external quantum efficiency is 4.01%. Compared with a monomolecular yellow light OLED device without an exciton diffusion layer, the efficiency and the performance of the device are greatly improved. Measuring the fluorescence quantum efficiency of the device to obtain 21.1% fluorescence quantum efficiency, and obtaining the fluorescence quantum efficiency by a formula eta_r＝EQE_max/(γ×η_PL×η_out) The exciton utilization of the device was calculated to be 95.12%. The yellow light material 2- (benzothiazole-2-yl) -4- (phenanthrene-9-yl) phenol is proved to have higher exciton utilization rate. The results of the experiment are shown in FIGS. 8 to 11.

Example 3:

the white OLED device comprises an organic light emitting layer and an exciton diffusion layer, wherein the organic light emitting layer is doped with an organic yellow fluorescence excited state proton transfer material and a classic high-efficiency blue light TADF material DMAC-DPS, and the exciton diffusion layer is the organic yellow fluorescence excited state proton transfer material.

The OLED device is of a multi-layer structure which is overlapped up and down, and the white OLED device sequentially comprises a substrate, an anode layer, a hole injection layer, a hole transmission layer, an organic light emitting layer, an exciton diffusion layer, a hole blocking layer, an electron transmission layer, an electron injection layer and a cathode layer from bottom to top.

The specific manufacturing process of this embodiment is as follows:

the first step is as follows: cleaning ITO (indium tin oxide) glass, respectively ultrasonically cleaning the ITO glass with acetone, water and ethanol for 30min, and then drying in an oven for 1 h;

the second step is that: plasma treatment for 45 s;

the third step: vacuum evaporation of hole injection layer MoO on anode ITO glass₃The evaporation rate is 2Hz/s, and the thickness of the evaporation film is 0.8nm-1.5 nm;

the fourth step: in the hole injection layer MoO₃Vacuum evaporation cavityThe transmission layer mCP with the evaporation rate of 2Hz/s and the evaporation film thickness of 10nm-50 nm;

the fifth step: vacuum evaporating organic light-emitting layer DMAC-DPS (heterojunction bipolar transistor-PA) (3:1) on the hole transport layer, wherein the evaporation rate is 2Hz/s, and the total film thickness is 20nm-60 nm;

and a sixth step: on the organic light emitting layer, vacuum evaporation is carried out on HBT-PA used as an exciton diffusion layer, the evaporation rate is 2Hz/s, and the thickness is 2nm-10 nm;

the seventh step: and (2) vacuum evaporating DPEPO as a hole blocking layer on the exciton diffusion layer, wherein the evaporation rate is 2Hz/s, and the thickness is 10nm-50 nm:

eighth step: vacuum evaporating TPBI serving as an electron transport layer on the hole blocking layer, wherein the evaporation rate is 2Hz/s, and the thickness is 10nm-50 nm;

the ninth step: vacuum evaporating LiF as an electron injection layer on the electron transport layer, wherein the evaporation rate is 0.1Hz/s, and the thickness is 0.8nm-1.3 nm;

the tenth step: and vacuum evaporating cathode Al on the electron injection layer to a thickness of 100nm-200 nm.

The device structure of the white OLED device in the embodiment is ITO/MoO₃mCP/DMAC-DPS, HBT-PA/HBT-PA/DPEPO/TPBI/LiF/Al, as shown in FIG. 12, the pressure is less than 1.0X 10 during vacuum evaporation^-3Pa, wherein the compounds 2- (benzothiazol-2-yl) -4- (phenanthren-9-yl) phenol and DMAC-DPS are used as the light-emitting material of the device.

The device is subjected to OLED property test, and the maximum current density of the device is 247.49mA/cm²Maximum luminance of 4254.3cd/m²The electroluminescence spectrum does not change obviously under the randomly selected five voltages. The maximum current efficiency is 16.84cd/A, the maximum power efficiency is 15.11lm/W, and the maximum external quantum efficiency is 13.57 cd/A. At a luminance of 100cd/A, the color coordinate was (0.3030,0.4423), and blue-white light emission was exhibited. The thin film absorption and emission spectra of the two luminescent materials were tested, and the emission spectrum of DMAC-DPS was not overlapped with the absorption spectrum of HBT-PA, indicating that there was no energy transfer between yellow light emission and blue light emission, and the white light device was a non-energy transfer mechanism. The results of the experiment are shown in FIGS. 13 to 17.

The invention provides a high-efficiency organic yellow fluorescence excited state proton transfer material based on high-energy-level reverse intersystem crossing, and a classic TADF blue light material and the yellow light material are doped to be used as a light emitting layer to prepare a white light OLED device. The yellow fluorescence excited state proton transfer material is simple to prepare and low in price, and the monomolecular yellow light OLED and the white light OLED have high device efficiency and high exciton utilization rate, the proportion is easy to regulate and control, and the device repeatability is good. The white light emitting layer is based on a non-energy transfer system, and blue light material emission and yellow light material emission cannot be influenced mutually, so that the color coordinate and the electroluminescence spectrum are stable, and the white light emitting layer has high use and popularization values.

The invention also provides reference for other related problems in the same field, can be expanded and extended on the basis of the reference, is applied to other related technical schemes in the field of organic electroluminescence, and has very wide application prospect.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein, and any reference signs in the claims are not intended to be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.