Organic single crystal OLED device based on anthryl derivative and preparation method thereof
By introducing terminal modification of end-based groups into anthracene derivative materials, changing the molecular stacking mode, and regulating charge transport and luminescence efficiency, the contradiction between organic single-crystalline OLED devices has high carrier mobility and strong fluorescence emission capabilities is solved, and a high-performance organic single-crystalline blue-ray OLED device is achieved, with an external quantum efficiency of 3.46%.
Patent Information
- Application Number
- CN202510204445.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-05-16
AI Technical Summary
There are contradictions in organic single-crystalline OLED devices in terms of high carrier mobility and strong fluorescence emission capabilities, resulting in low external quantum efficiency (EQE), limiting the further application and development of the device.
By introducing terminal modification end-based groups into anthracene derivative materials, the accumulation mode of molecules within the crystal is changed, and charge transport, luminescence efficiency and optical coupling output characteristics are regulated. The specific method includes using 2,6-bis(6-tert-butylnaphthalene)anthracene (TBU-DNA) as the luminescent layer material and optimizing the device structure by reasonably selecting the charge transport layer and charge barrier layer materials.
The high performance of organic single crystal blue light OLED devices has been achieved, with an external quantum efficiency (EQE) reaching 3.46%, which is the highest value among OLED devices based on organic single crystal luminescent layer, which is close to the theoretical limit.
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Figure CN120018691A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of organic light emitting diodes, in particular to an anthracene derivative-based organic single crystal OLED device and a preparation method thereof. Background Art
[0002] Organic light-emitting diodes (OLEDs) have many advantages, such as low power consumption, high contrast, wide color gamut, fast response speed, light weight, and bendability. They are gradually replacing traditional LCD and LED devices and becoming the mainstream technology in high-end flat panel display and solid-state lighting applications. In recent years, although OLED technology has made great achievements in the display field, there are still some technical difficulties that hinder the development of devices and limit the further improvement of the electroluminescent performance of devices. Organic single-crystal semiconductor materials have become a potential material system for the development of high-performance optoelectronic devices due to their many advantages, thus attracting more and more attention from academia and industry. Researchers have been committed to developing OLED devices based on organic single-crystal materials, with the goal of achieving higher-performance electroluminescence and better device performance. However, due to process and material limitations, compared with traditional amorphous OLED devices, the external quantum efficiency (EQE) of such organic single-crystal OLED devices is still relatively low, basically below 3%, which will seriously hinder the further application and development of this type of device.
[0003] Analysis shows that one of the main reasons is that organic single crystals cannot have both high carrier mobility and strong fluorescence emission capabilities. This is because these two characteristics are contradictory. For example, face-to-face stacking in the crystal structure is more conducive to carrier transport, but H aggregation will cause fluorescence quenching; head-to-tail stacking is conducive to J aggregation fluorescence emission, but is not conducive to carrier transport. In addition, the EQE of OLED devices not only depends on the fluorescence quantum yield of the material itself, but also has a lot to do with the molecular arrangement and dipole orientation in the light-emitting layer material. Since the direction of the molecular dipole is basically parallel to the long axis of the molecule, and the strongest luminescence angle is perpendicular to the direction of the molecular dipole, the luminescent molecules that are closer to being parallel to the device plane are easier to couple light output inside the device.
[0004] In the early stage of single crystal OLED device research, attempts were made to use single crystal semiconductor materials such as thiophene benzene polymers, bisphenylene derivatives, and anthracene derivatives as the light-emitting layer of OLED devices. However, thiophene benzene polymer molecular materials are mostly perpendicular to the crystal plane in the crystal, showing strong self-waveguide and edge emission phenomena, which are not suitable for surface-generated OLED devices and have poor photon extraction efficiency, affecting the electroluminescence efficiency of OLED devices. Although bisphenylene derivatives show high fluorescence quantum yield, their mobility is around 10 -1 -10 -2 cm 2 V -1 s -1The material cannot have both high mobility and strong fluorescence performance, and the EQE of OLED devices is mostly at the level of 0.1%, which is difficult to improve further; DPA single crystal materials, a typical representative of anthracene derivatives, have both high mobility and strong fluorescence characteristics, but their higher HOMO energy level is difficult to match with metal electrodes, and the molecular stacking mode is basically perpendicular to the crystal plane, and the EQE of the single crystal OLED device is also much lower than that of amorphous OLED devices. In order to further improve the performance of single crystal OLED devices, can we use reasonable molecular material design and crystal engineering regulation to improve material performance through molecular end group modification, give organic single crystal materials the characteristics of high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency, and finally realize high-performance single crystal OLED devices based on this type of single crystal material? However, the design of such single crystal materials and the preparation of single crystal OLED devices are still a difficult problem that needs to be solved urgently. Summary of the invention
[0005] The purpose of the present invention is to provide an anthracene derivative-based organic single crystal OLED device and a preparation method thereof, based on an anthracene derivative material system, by modifying the end group at the end, changing the stacking mode of the molecule inside the crystal, and regulating the charge transport, luminous efficiency, light coupling output and other characteristics. Based on TBU-DNA organic single crystal as the light-emitting layer material, the device structure is optimized by rationally selecting the charge transport layer and charge blocking layer materials, and finally a high-performance organic single crystal blue light OLED device is constructed.
[0006] To achieve the above-mentioned purpose, the present invention provides an organic single crystal OLED device based on anthracene derivatives, comprising an organic single crystal material and a substrate, wherein the organic single crystal material is located on the substrate, a hole blocking layer and an electron transport layer are deposited on the surface of the organic single crystal material, cathode deposition is performed on the electron transport layer, a photoresist is dripped on the cathode surface and cured, and an anode modification layer and an anode are evaporated on the other surface of the organic single crystal material.
[0007] Preferably, the organic single crystal material is 2,6-di(6-tert-butylnaphthalene)anthracene, which is used as the light-emitting layer of the OLED device.
[0008] Preferably, the hole blocking layer is di[2-((oxy)diphenylphosphino)phenyl]ether and has a thickness of 10-15 nm.
[0009] Preferably, the electron transport layer is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine and has a thickness of 40-45 nm.
[0010] Preferably, the cathode is a Ca / Ag composite electrode with thicknesses of Ca 3-5nm and Ag 80-100nm respectively.
[0011] Preferably, the photoresist model is NOA63, the dosage is 50-200 μL, and the curing time is 5-10 min.
[0012] Preferably, the anode modification layer is MoO3 with a thickness of 5 nm; the anode is an Ag electrode with a thickness of 15-20 nm.
[0013] The present invention also provides a method for preparing an anthracene derivative-based organic single crystal OLED device, comprising the following steps: Step 1: Growth and preparation of organic single crystals: 1-2 mg of organic single crystal material powder is taken and placed in the high-temperature sublimation zone of a dual-temperature quartz tube furnace, and then the temperature and growth time of the sublimation zone and the crystallization zone are set respectively, and a high-purity inert gas with a stable flow rate is introduced into the tube furnace, and the organic single crystal sheet is finally obtained on the quartz tube wall after growth for 2 hours based on the physical vapor transport method; Step 2, substrate pretreatment: ultrasonically clean the substrate in a cleaning agent, then use high-pressure nitrogen to blow away the residual solvent on the surface, place the cleaned substrate in a culture dish, drop a hydrophobic modifier in the center of the culture dish, cover the culture dish, put the culture dish in a vacuum oven, use heating to volatilize the hydrophobic modifier and perform hydrophobic treatment on the substrate surface, after the treatment is completed, take out the substrate, perform ultrasonic cleaning again, and use high-pressure nitrogen to blow off the solvent, and finally standby; Step 3, preparation of OLED device based on organic single crystal light-emitting layer: transfer the thin sheet organic single crystal material grown in step 1 to the hydrophobic substrate treated in step 2 using tweezers, cover the substrate device with organic single crystal material with an organic layer mask, and place it in a vacuum evaporation device, deposit a hole blocking layer and an electron transport layer on the surface of the organic single crystal material by vacuum thermal evaporation in turn, then replace it with a cathode mask, continue cathode deposition, take the device out of the vacuum evaporator, add photoresist on the surface of the device, cover it with a transfer glass sheet and apply pressure, after the photoresist diffuses and covers the entire device, expose it to ultraviolet light to cure the photoresist, then use a blade to peel the device from the hydrophobic substrate and transfer it to a glass substrate, cover it with an anode mask again, place it in a vacuum evaporation device, evaporate the anode modification layer and the anode in turn, and complete the preparation of the entire device.
[0014] The advantages and beneficial effects of the present invention using the above-mentioned anthracene-based organic single crystal OLED device and its preparation method are: The organic single crystal material of the present invention is 2,6-di(6-tert-butylnaphthalene)anthracene (TBU-DNA). The 2,6-di(6-tert-butylnaphthalene)anthracene molecules can simultaneously have the characteristics of high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency through the stacking of sliding herringbone structures. The device structure is optimized by rationally selecting charge transport layer and charge blocking layer materials, and finally a high-performance organic single crystal blue light OLED device is constructed. The EQE of the obtained device is the highest value among OLED devices based on organic single crystal light-emitting layers.
[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 Characterization of the anthracene derivatives used in the present invention, wherein (a) is the molecular slip herringbone stacking structure of TBU-DNA single crystal, (b) is the X-ray diffraction spectrum of TBU-DNA organic single crystal, and (c) is the photoluminescence spectrum characterization of TBU-DNA organic single crystal; Figure 2 The photoelectric properties of the anthracene derivatives used in the present invention, wherein (a) is the photoluminescence quantum yield of the TBU-DNA organic single crystal, and (b) is the hole mobility-electric field intensity relationship diagram of the TBU-DNA organic single crystal; Figure 3 The present invention is based on anthracene derivative organic single crystal OLED device structure, wherein (a) is a device structure diagram, wherein (b) is a device energy level structure diagram; Figure 4 The performance diagram of OLED devices with TBU-DNA organic single crystal as the light-emitting layer, where (a) is the current density-voltage curve and the brightness-voltage relationship curve, (b) is the electroluminescence intensity-wavelength relationship curve, (c) is the current efficiency-brightness relationship curve, and (d) is the external quantum efficiency-brightness relationship curve. DETAILED DESCRIPTION
[0017] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.
[0018] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.
[0019] Unless otherwise defined, the reagents and equipment used in the present invention can be obtained through regular commercial channels.
[0020] Example 1 The present invention uses a sheet-like organic single crystal TBU-DNA (2,6-di(6-tert-butylnaphthalene)anthracene) grown by a physical vapor transport method as the light-emitting layer of the device, and utilizes the characteristics of the organic single crystal with high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency to improve the electroluminescent performance of OLED.
[0021] The organic single crystal OLED device based on anthracene derivatives includes an organic single crystal material and a substrate. The organic single crystal material is located on the substrate. A hole blocking layer and an electron transport layer are deposited on the surface of the organic single crystal material. A cathode is deposited on the electron transport layer. A photoresist is dripped on the cathode surface and cured. An anode modification layer and an anode are evaporated on the other surface of the organic single crystal material.
[0022] The preparation method of an organic single crystal OLED device based on anthracene derivatives comprises the following specific steps: (1) Growth and preparation of 2,6-di(6-tert-butylnaphthalene)anthracene (TBU-DNA) organic single crystals: First, 2 mg of TBU-DNA powder was placed in the high-temperature sublimation zone of a dual-temperature quartz tube furnace. Next, high-purity argon was introduced into the tube furnace as a carrier gas to transport the sublimated material to the crystallization zone, and the carrier gas flow rate was kept stable at 36 mL / min. Subsequently, the growth parameters of the tube furnace were set, with the temperature of the high-temperature sublimation zone at 350°C, the temperature of the low-temperature crystallization zone at 320°C, and the growth time set to 150 minutes, and the growth of organic single crystal materials began. After growth using physical vapor transport (PVT), thin flakes of organic single crystal materials will form on the quartz tube wall.
[0023] (2) Preparation of hydrophobic Si substrate: First, a single-sided polished silicon substrate with a size of 1.4 cm × 1.6 cm was placed in acetone, ethanol and isopropanol for ultrasonic cleaning for 30 minutes. After cleaning, the residual solvent on the surface was blown off with high-pressure nitrogen. Next, the silicon substrate was placed in a culture dish, and 30 μL of hydrophobic modifier (OTS) was taken with a pipette, dripped into the center of the culture dish, and sealed with a lid. Subsequently, the entire culture dish was placed in a vacuum oven, and the vacuum degree of the oven was set to 0.1 MPa, the temperature was set to 60 ° C, and the treatment time was 4 hours to volatilize OTS and hydrophobicize the surface of the silicon substrate. Finally, the silicon substrate that had completed the hydrophobic treatment was ultrasonically cleaned again with acetone, ethanol and isopropanol for 30 minutes, and then the solvent was blown dry with high-pressure nitrogen. The treated substrate can be used later.
[0024] (3) Preparation of high-performance blue OLEDs based on TBU-DNA single crystal light-emitting layers; The TBU-DNA organic single crystal grown in step (1) was transferred to the hydrophobic Si substrate treated in step (2); after covering with an organic mask, the wafer was placed in a vacuum coating apparatus and the vacuum degree reached 5×10 -4 After Pa, the hole blocking layer and the electron transport layer were evaporated. The hole blocking layer was di[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO) with an evaporation rate of 1.2Å / s and a thickness of 10nm. The electron transport layer was 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]bipyridine (TmPyPB) with an evaporation rate of 1.2Å / s and a thickness of 40nm. Then, the cathode mask was replaced and the Ca / Ag composite electrode was evaporated with a thickness of 3nm. and 80nm, with deposition rates of 0.3Å / s and 1.25Å / s, respectively; next, add NOA63 photoresist to the surface of the device and cover it with a glass sheet to press it tightly. After the photoresist diffuses to the edge of the entire glass, expose the device to ultraviolet light for 5 minutes to solidify the photoresist; then use a blade to peel the device from the substrate and transfer it to a glass substrate; then place the device in a vacuum evaporator again, cover it with an anode mask, and evaporate MoO3 and Ag in turn, with thicknesses of 5nm and 20nm, respectively, with controlled deposition rates of 0.3Å / s and 1.2Å / s, respectively. The schematic diagram of the structure based on TBU-DNA single crystal is shown in the figure. Figure 3 As shown, the preparation of OLED based on TBU-DNA single crystal light-emitting layer is completed, and then the electroluminescent performance of the device is tested.
[0025] Due to the difficulty in obtaining organic single crystal materials with high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency, the device performance of OLED based on organic single crystals has always been poor. In order to obtain high-performance organic single crystal blue light OLED devices, an anthracene derivative TBU-DNA with a sliding herringbone molecular stacking pattern was obtained by molecular modification. Through systematic research, it was found that the reasonable molecular stacking pattern of TBU-DNA single crystal plays a vital role in changing the optoelectronic properties, making it have the characteristics of high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency. Furthermore, high-performance organic single crystal blue light OLED devices were prepared using TBU-DNA molecules. The external quantum efficiency (EQE) of the surface-emitting OLED device based on TBU-DNA organic single crystal can reach 3.46%, which is the highest value reported so far for OLED devices based on organic single crystal light-emitting layers.
[0026] Figure 1 It was shown that the organic single crystal material 2,6-di(6-tert-butylnaphthalene)anthracene molecules slipped along the long axis of the molecule, thus forming a herringbone molecular stacking structure. The grown single crystals had a blue light photoluminescence spectrum and a strong X-ray diffraction peak, which indicated that the single crystal growth quality was good.
[0027] Figure 2 The photoelectric properties of organic single crystal 2,6-di(6-tert-butylnaphthalene)anthracene molecules are demonstrated. The herringbone sliding stacking brings about high quantum yield of organic single crystals and high hole mobility along the c-axis, that is, the carrier transport direction in the device, which makes it have great potential to become the light-emitting layer of OLED devices.
[0028] Figure 3 The energy level structure and thickness of each layer of the organic single crystal device are shown in Figure 1. Having a suitable energy level structure can further improve the performance of the organic single crystal device.
[0029] Figure 4 This is an electroluminescent performance diagram of an organic single crystal OLED device based on anthracene derivatives. It can be seen from the figure that the single crystal device prepared in Example 1 exhibits high-efficiency electroluminescent performance. Among them, the maximum brightness of the single crystal blue OLED is 1880 candelas per square meter, the maximum current efficiency is 5.48 candelas per ampere, and the maximum external quantum efficiency is 3.46%, which is the highest value among organic single crystal devices at present, close to the theoretical limit of 4.09%. The device of Example 1 of the present invention exhibits high-efficiency performance, indicating that the strategy of using an organic single crystal material with high carrier mobility, high fluorescence quantum yield, and high light coupling output efficiency as the light-emitting layer proposed in the present invention is feasible for improving the performance of organic single crystal blue OLED devices.
[0030] Therefore, the present invention adopts the above-mentioned anthracene-based organic single crystal OLED device and its preparation method, based on the anthracene-based material system, by modifying the terminal end group, changing the stacking mode of the molecule inside the crystal, and regulating the charge transport, luminous efficiency, light coupling output and other characteristics. Based on TBU-DNA organic single crystal as the light-emitting layer material, the device structure is optimized by rationally selecting the charge transport layer and charge blocking layer materials, and finally constructing a high-performance organic single crystal blue light OLED device.
[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.
Claims
1. An organic single crystal OLED device based on anthracene derivatives, comprising an organic single crystal material and a substrate, characterized in that: The organic single crystal material is located on a substrate, a hole blocking layer and an electron transport layer are deposited on the surface of the organic single crystal material, cathode deposition is performed on the electron transport layer, photoresist is dripped on the cathode surface and cured, and an anode modification layer and an anode are evaporated on the other surface of the organic single crystal material.
2. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The organic single crystal material is an anthracene-based derivative material of 2,6-di(6-tert-butylnaphthalene)anthracene, which is used as the light-emitting layer of the OLED device.
3. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The hole blocking layer is di[2-((oxy)diphenylphosphino)phenyl]ether and has a thickness of 10-15 nm.
4. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The electron transport layer is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]bipyridine and has a thickness of 40-45 nm.
5. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The cathode is a Ca / Ag composite electrode, with thicknesses of Ca 3-5nm and Ag 80-100nm respectively.
6. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The photoresist model is NOA 63, the dosage is 50-200 μL, and the curing time is 5-10 minutes.
7. The organic single crystal OLED device based on anthracene derivatives according to claim 1, characterized in that: The anode modification layer is MoO3 with a thickness of 5nm; the anode is an Ag electrode with a thickness of 15-20nm.
8. The method for preparing an anthracene derivative-based organic single crystal OLED device according to any one of claims 1 to 7, characterized in that: The steps include: Step 1: Growth and preparation of organic single crystals: 1-2 mg of organic single crystal material powder is taken and placed in the high-temperature sublimation zone of a dual-temperature quartz tube furnace, and then the temperature and growth time of the sublimation zone and the crystallization zone are set respectively, and a high-purity inert gas with a stable flow rate is introduced into the tube furnace, and the organic single crystal sheet is finally obtained on the quartz tube wall after growth for 2 hours based on the physical vapor transport method; Step 2, substrate pretreatment: ultrasonically clean the substrate in a cleaning agent, then use high-pressure nitrogen to blow away the residual solvent on the surface, place the cleaned substrate in a culture dish, drop a hydrophobic modifier in the center of the culture dish, cover the culture dish, put the culture dish in a vacuum oven, use heating to volatilize the hydrophobic modifier and perform hydrophobic treatment on the substrate surface, after the treatment is completed, take out the substrate, perform ultrasonic cleaning again, and use high-pressure nitrogen to blow off the solvent, and finally standby; Step 3, preparation of OLED device based on organic single crystal light-emitting layer: transfer the thin sheet organic single crystal material grown in step 1 to the hydrophobic substrate treated in step 2 using tweezers, cover the substrate device with organic single crystal material with an organic layer mask, and place it in a vacuum evaporation device, deposit a hole blocking layer and an electron transport layer on the surface of the organic single crystal material by vacuum thermal evaporation in turn, then replace it with a cathode mask, continue cathode deposition, take the device out of the vacuum evaporator, add photoresist on the surface of the device, cover it with a transfer glass sheet and apply pressure, after the photoresist diffuses and covers the entire device, expose it to ultraviolet light to cure the photoresist, then use a blade to peel the device from the hydrophobic substrate and transfer it to a glass substrate, cover it with an anode mask again, place it in a vacuum evaporation device, evaporate the anode modification layer and the anode in turn, and complete the preparation of the entire device.