Organic europium complex based on phenanthroline derivative and electroluminescent device thereof

Abstract

The invention belongs to the technical field of luminescent devices, and discloses an organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof, the organic europium complex comprises a derivative design module, a europium complex core module, a multilayer device module and a packaging module; the phenanthroline derivative and the auxiliary ligand both adopt an environment-friendly synthesis process, so that the generation of harmful wastes is reduced, and support is provided for sustainable development. The prepared europium complex OLEDs have excellent red light performance and can be widely applied to the fields of high-precision display, agricultural illumination and biomedical treatment. The invention discloses an organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof, and remarkably solves the problems of low luminous efficiency, poor device stability and complex material design in the prior art. By optimizing the ligand structure and the system design, the energy transfer efficiency, the luminescence performance and the device stability are remarkably improved, and an innovative technical path is provided for research, development and industrial application of a high-performance red light OLED.

Description

Technical Field

[0001] The present invention belongs to the technical field of light-emitting devices, and particularly relates to an organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof. Background Art

[0002] Currently, organic europium complexes are widely used in organic electroluminescent devices (OLEDs) due to their unique narrow-band red light emission performance. For example, Patent Document CN104578651A describes an organic luminescent material based on a europium complex, which enhances the luminescence efficiency by introducing a complex ligand structure.

[0003] Through the above analysis, the problems and defects existing in the prior art are as follows:

[0004] (1) Low luminescence efficiency: The luminescence of europium complexes mainly depends on the efficiency of energy transfer from the ligand to the europium ion (energy transfer). However, due to the limitation of the intrinsic quantum efficiency, the overall luminescence performance is low.

[0005] (2) Insufficient device stability: The thermal stability and photochemical stability of europium complexes are poor, which limits their application at high temperatures or during long-term operation.

[0006] (3) Complex ligand design: Existing ligand structures are difficult to simultaneously achieve both efficient energy transfer and good solubility, resulting in a complex material preparation process. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides an organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof.

[0008] The present invention is implemented as follows. An organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof include:

[0009] A derivative design module, a europium complex core module, a multi-layer device module, and a packaging module;

[0010] The derivative design module, connected to the europium complex core module, is used to adjust its energy level by introducing specific substituents into the phenanthroline molecular structure to optimize the energy transfer efficiency to the europium ion; specific substituents include fluorine, methoxy, amino, or carbonyl to enhance intermolecular π-π stacking and intramolecular energy transfer;

[0011] The europium complex core module, connected to the multi-layer device module, is used to use a phenanthroline derivative as the main ligand and coordinate with the europium ion to form a stable complex; an auxiliary ligand is introduced to adjust the thermal stability and photophysical properties of the complex;

[0012] Multilayer device module, connected to the encapsulation module, for light emission, electron transport, and hole transport;

[0013] Encapsulation module, connected to the multilayer device module, for combining the water-oxygen barrier technology through vacuum encapsulation.

[0014] Furthermore, the derivative design module:

[0015] (1) Molecular design

[0016] Introduce methoxy groups at the 2- and 9-positions of the phenanthroline molecule to increase the energy level of the ligand;

[0017] Introduce fluorine or carbonyl groups at the 3- and 8-positions of the phenanthroline to regulate the π-π stacking and energy transfer channels between molecules;

[0018] (2) Synthesis route

[0019] Use phenanthroline as the starting material and introduce substituents by Friedel-Crafts reaction or Grignard reagent;

[0020] Obtain high-purity phenanthroline derivatives through purification technology;

[0021] (3) Energy level testing and optimization

[0022] Use cyclic voltammetry and ultraviolet-visible absorption spectroscopy to determine the HOMO and LUMO energy levels of the ligand;

[0023] Select the phenanthroline derivative with the best energy level matching the Eu(III) energy level as the ligand.

[0024] Furthermore, the europium complex core module:

[0025] 1) Complex preparation

[0026] Dissolve the designed phenanthroline derivative in anhydrous acetonitrile;

[0027] Add europium ion precursor and β-diketone auxiliary ligand;

[0028] Stir and react at 80 °C for 2 hours, slowly evaporate the solvent to let the complex precipitate as crystals, and generate a stable europium complex;

[0029] 2) Structure characterization

[0030] Use elemental analysis, X-ray diffractometer, infrared spectroscopy, and nuclear magnetic resonance to characterize the coordination structure of the complex;

[0031] Use thermogravimetric analysis to evaluate the thermal stability of the complex, and require the decomposition temperature to be higher than 250 °C;

[0032] 3) Luminescence performance testing

[0033] Test the photoluminescence spectrum and electroluminescence spectrum of the europium complex to confirm the intensity and monochromaticity of its red emission peak at 612 nm;

[0034] Evaluate the luminescence efficiency through quantum yield testing to ensure that the efficiency is significantly higher than that of the prior art;

[0035] Furthermore, the multi-layer device module:

[0036] (1) ITO substrate treatment

[0037] Ultrasonically clean the ITO glass with ethanol and isopropanol, and after drying, perform ultraviolet ozone treatment to enhance surface hydrophilicity and improve hole injection;

[0038] (2) Deposition of the hole transport layer

[0039] Uniformly coat the PEDOT:PSS solution on the ITO surface and prepare a thin film by spin coating;

[0040] Anneal at 120 °C for 15 minutes to form a uniform and flat hole transport layer;

[0041] (3) Deposition of the light-emitting layer

[0042] Prepare a mixed solution of the europium complex and the electron transport material;

[0043] Deposit the light-emitting layer by spin coating, controlling the film thickness to be about 60 nm;

[0044] (4) Deposition of the electron transport layer

[0045] Use a metal oxide material to prepare the electron transport layer and uniformly coat it on the light-emitting layer;

[0046] Anneal at 150 °C for 30 minutes to enhance the film density and electron transport performance;

[0047] (5) Deposition of the cathode electrode

[0048] Deposit a metal cathode on the electron transport layer using vacuum evaporation.

[0049] Furthermore, the encapsulation module:

[0050] 1) Vacuum encapsulation

[0051] Cover the device surface with a glass cover plate and seal it with ultraviolet curable glue around;

[0052] Complete the encapsulation in a vacuum chamber to prevent air and moisture from infiltrating;

[0053] 2) Water and oxygen barrier film.

[0054] Furthermore, the water and oxygen barrier film:

[0055] Coat a multi-layer inorganic / organic composite water and oxygen barrier film on the device surface, and construct the composite film by atomic layer deposition technology;

[0056] The oxygen transmission rate of the barrier film needs to be lower than 10 -6 g / m 2 ·day to ensure the chemical stability of the europium complex during operation.

[0057] Another object of the present invention is to provide an organic europium complex based on a phenanthroline derivative and a method for designing an electroluminescent device thereof, including:

[0058] Step 1, through the derivative design module, introduce specific substituents into the phenanthroline molecular structure to adjust its energy level to optimize the energy transfer efficiency to europium ions; specific substituents include fluorine, methoxy, amino or carbonyl to enhance intermolecular π-π stacking and intramolecular energy transfer;

[0059] Step 2, through the europium complex core module, use the phenanthroline derivative as the main ligand and coordinate with europium ions to form a stable complex; introduce auxiliary ligands to adjust the thermal stability and photophysical properties of the complex;

[0060] Step 3, through the multi-layer device module, emit light, transport electrons, and transport holes;

[0061] Step 4, through the encapsulation module, use vacuum encapsulation combined with water and oxygen barrier technology.

[0062] Another object of the present invention is to provide a computer device, the computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for designing an organic europium complex based on a phenanthroline derivative and its electroluminescent device.

[0063] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the processor executes the steps of the method for designing an organic europium complex based on a phenanthroline derivative and its electroluminescent device.

[0064] Another object of the present invention is to provide an information data processing terminal, and the information data processing terminal is used to implement the organic europium complex based on a phenanthroline derivative and its electroluminescent device.

[0065] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are:

[0066] Improve the energy transfer efficiency and luminescence efficiency of europium complexes. Enhance the thermal stability and photochemical stability of europium complexes. Simplify the material design and preparation process and reduce the complexity in applications.

[0067] 1. Substantially improved luminescence efficiency:

[0068] The phenanthroline derivative significantly improves the energy transfer efficiency to europium ions through precise energy level matching.

[0069] The luminescence efficiency of the device is increased by more than 30% compared with the prior art, achieving higher light output.

[0070] 2. Significantly enhanced device stability:

[0071] The thermal decomposition temperature of the newly designed europium complex is increased to above 250 °C, significantly enhancing the thermal stability.

[0072] Vacuum packaging and water and oxygen barrier technologies effectively reduce the damage of the external environment to the device, and the device life is extended to 1.5 times that of the prior art.

[0073] 3. Simplified material design and preparation:

[0074] The selection of substituents of the phenanthroline derivative significantly improves the solubility and processability of the ligand, reducing the complexity of material preparation.

[0075] The luminescent layer adopts a solution processing technology, simplifying the multi-layer deposition steps in the traditional vacuum evaporation method and reducing the production cost.

[0076] 4. Improved energy utilization efficiency:

[0077] The newly designed multi-layer structure improves the charge injection efficiency and energy utilization rate by optimizing the hole and electron transport paths, reducing the energy loss of non-radiative recombination.

[0078] 5. Green and environmental protection characteristics:

[0079] Both the phenanthroline derivative and the auxiliary ligand adopt environmentally friendly synthesis processes, reducing the generation of harmful waste and providing support for sustainable development.

[0080] 6. Expansion of device application fields:

[0081] The prepared europium complex OLEDs have excellent red light performance and can be widely applied in the fields of high-precision display, agricultural lighting and biomedicine.

[0082] Organic europium complexes based on phenanthroline derivatives and their electroluminescent devices significantly solve the problems of low luminous efficiency, poor device stability, and complex material design in the prior art. By optimizing the ligand structure and system design, the energy transfer efficiency, luminescence performance, and device stability are significantly improved, providing an innovative technical path for the research and development and industrial application of high-performance red OLEDs. Brief Description of the Drawings

[0083] Figure 1 It is a structural block diagram of an organic europium complex based on phenanthroline derivatives and its electroluminescent device provided by an embodiment of the present invention.

[0084] Figure 2 It is a method flow chart of a derivative design module provided by an embodiment of the present invention.

[0085] Figure 3 It is a method flow chart of the design of an organic europium complex based on phenanthroline derivatives and its electroluminescent device provided by an embodiment of the present invention.

[0086] Figure 1 In it: 1. Derivative design module; 2. Europium complex core module; 3. Multilayer device module; 4. Encapsulation module. Detailed Embodiments

[0087] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0088] As Figure 1 shown, an organic europium complex based on phenanthroline derivatives and its electroluminescent device provided by an embodiment of the present invention include:

[0089] Derivative design module 1, europium complex core module 2, multilayer device module 3, and encapsulation module 4.

[0090] The derivative design module 1 is connected to the europium complex core module 2 and is used to adjust its energy level to optimize the energy transfer efficiency to europium ions by introducing specific substituents into the phenanthroline molecular structure; specific substituents include fluorine, methoxy, amino, or carbonyl to enhance intermolecular π-π stacking and internal energy transfer within the molecule;

[0091] The europium complex core module 2 is connected to the multilayer device module 3 and is used to use phenanthroline derivatives as the main ligand and coordinate with europium ions to form a stable complex; an auxiliary ligand is introduced to adjust the thermal stability and photophysical properties of the complex;

[0092] The multi-layer device module 3, connected to the encapsulation module 4, is used for light emission, electron transport, and hole transport;

[0093] The encapsulation module 4, connected to the multi-layer device module 3, is used to combine the water and oxygen barrier technology through vacuum encapsulation.

[0094] The derivative design module adjusts its electron distribution and energy level structure by introducing specific substituents (such as fluorine, methoxy, amino, or carbonyl) into the phenanthroline molecular structure. This optimized design can improve the energy transfer efficiency between the phenanthroline molecule and europium ions, while enhancing the π-π stacking effect between molecules and promoting the energy transfer within the molecule, laying the foundation for efficient light emission.

[0095] The europium complex core module uses phenanthroline derivatives as the main ligands, combines with europium ions through coordination bonds to form stable complexes, and introduces auxiliary ligands to further improve the thermal stability and photophysical properties. Through this molecular design, the complex can maintain good performance under high temperature or complex environments, while achieving high-efficiency optical excitation and luminescence efficiency.

[0096] The multi-layer device module includes a light-emitting layer, an electron transport layer, and a hole transport layer, each layer having specific functions. The europium complex, as the core material of the light-emitting layer, realizes red light emission by exciting europium ions through energy transfer; the electron transport layer and the hole transport layer are responsible for efficiently transporting electrons and holes to the light-emitting layer respectively, so as to realize the recombination of electrons and holes and generate photons.

[0097] In the multi-layer device module, when electrons and holes recombine in the light-emitting layer, the phenanthroline derivative transfers energy to europium ions efficiently, thus exciting the characteristic transition of europium ions and realizing red light emission with high brightness and good purity. This energy transfer mechanism combined with the optimized multi-layer structure design can significantly improve the luminescence efficiency and color purity of the device.

[0098] The encapsulation module adopts vacuum encapsulation technology combined with water and oxygen barrier materials to protect the device from the influence of external moisture and oxygen. This process can delay the degradation of organic materials, significantly improve the stability and lifespan of the electroluminescent device, and ensure that it can still maintain high-efficiency performance during long-term operation.

[0099] Through the collaborative work of the derivative design module, the europium complex core module, the multi-layer device module, and the encapsulation module, an electroluminescent device with high efficiency, stability, and long-term operability is finally realized. Based on the optimization of optoelectronic properties, this device has excellent thermal stability, luminescence efficiency, and color purity, and can be widely used in fields such as displays, lighting, and optical sensing.

[0100] As Figure 2 shown, the derivative design module provided by the embodiment of the present invention:

[0101] S101, Molecular Design

[0102] Introduce methoxy groups at the 2- and 9-positions of the phenanthroline molecule to increase the energy level of the ligand;

[0103] Introduce fluorine or carbonyl groups at the 3- and 8-positions of phenanthroline to regulate the π-π stacking and energy transfer channels between molecules;

[0104] S102, Synthesis Route

[0105] Use phenanthroline as the starting material and introduce substituents by Friedel-Crafts reaction or Grignard reagent;

[0106] Obtain high-purity phenanthroline derivatives through purification techniques;

[0107] S103, Energy Level Testing and Optimization

[0108] Use cyclic voltammetry and ultraviolet-visible absorption spectroscopy to measure the HOMO and LUMO energy levels of the ligand;

[0109] Select the phenanthroline derivative with the best energy level matching the Eu(III) energy level as the ligand.

[0110] In the embodiments of the present invention, to achieve precise regulation of the energy levels of phenanthroline derivatives, first introduce methoxy groups at specific positions (2- and 9-positions) of the phenanthroline molecule to increase the energy level of the molecule, thereby providing a more suitable electron donor-acceptor environment for subsequent coordination with Eu(III). In addition, introducing fluorine or carbonyl groups at the 3- and 8-positions can not only enhance the stability of the molecule by regulating the π-π stacking between molecules but also be beneficial to the energy transfer channel, ensuring that phenanthroline has broader application potential in the field of functional materials.

[0111] In the actual preparation process of the derivative, use phenanthroline as the basic starting material and selectively introduce substituents such as methoxy, fluorine, or carbonyl groups to the specified positions (2- and 9-positions or 3- and 8-positions) by Friedel-Crafts reaction or Grignard reagent. This chemical reaction process pays attention to the precise control of reaction conditions (such as temperature, solvent, catalyst, etc.) to ensure that the substituents can be effectively grafted onto the phenanthroline molecular skeleton. Through subsequent purification means, including recrystallization, column chromatography, or high-performance liquid separation, etc., obtain high-purity phenanthroline derivatives to meet the high-precision requirements for subsequent energy level testing.

[0112] To evaluate the potential of the synthesized derivatives in the luminescence properties of the complexes, the present invention precisely measures the frontier orbital energy levels (HOMO and LUMO) of the derivatives by cyclic voltammetry and ultraviolet-visible absorption spectroscopy. Cyclic voltammetry can determine the ability of a molecule to gain or lose electrons, while ultraviolet-visible absorption spectroscopy provides specific information on the energy absorption and transition of the molecule. By comparing the measured HOMO and LUMO energy levels with those of Eu(III), it is possible to quickly determine whether the derivative has a good energy level match with Eu(III), thereby selecting the derivative with the highest luminescence efficiency and stability.

[0113] Based on the above test results, the present invention further optimizes the structural design and substituent combination of the derivative molecules, while ensuring good energy level matching, maintaining the molecular stability and the processability of the material. Through continuous structural modification and adjustment of the synthesis process, phenanthroline derivatives with higher luminescence efficiency and better color purity when complexed with Eu(III) can be obtained, laying a foundation for their wide application in functional material fields such as display, lighting, or sensing detection. This method provides a scientific, feasible, and popularizable technical idea for the subsequent development of more high-performance organic complexes.

[0114] The present invention prepares highly luminescent europium complexes through coordination chemistry design. First, the phenanthroline derivative is used as the main ligand and dissolved in anhydrous acetonitrile to ensure an anhydrous and anaerobic reaction environment, so as to improve the purity and stability of the complex. Then, the europium ion precursor (such as EuCl3 or Eu(NO 3 ) 3 ) is slowly added, and at the same time, β-diketone auxiliary ligands such as acetylacetone (Acac) or thenoyltrifluoroacetone (TTA) are added to promote the coordination stability of the europium ions. After stirring at 80 °C for 2 hours, the solvent is gradually evaporated to precipitate the complex, and finally a structurally stable europium complex is formed.

[0115] To confirm the structure of the complex, the present invention uses elemental analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) techniques for detailed characterization to ensure the correctness of the coordination structure. Further, the thermal stability of the europium complex is evaluated by thermogravimetric analysis (TGA) to ensure its stable performance in high-temperature luminescence devices. It is required that the decomposition temperature (T 50 ) of the complex is higher than 250 °C to prevent degradation during long-term operation and improve the device life.

[0116] The present invention tests the photoluminescence (PL) and electroluminescence (EL) spectra of europium complexes, focusing on the intensity of the red emission peak at 612 nm and the spectral monochromaticity, to ensure its high-purity red light emission characteristics. In addition, the photoluminescence quantum yield (PLQY) test is used to evaluate the luminescence efficiency, ensuring that the luminescence efficiency of the europium complex is higher than that of traditional europium complex materials (>50%), so as to improve the overall brightness and energy utilization efficiency of the device.

[0117] To construct a high-performance light-emitting device, the present invention optimizes the multilayer OLED structure. First, the ITO substrate is cleaned by ultrasonic cleaning (ethanol, isopropanol) + ultraviolet ozone treatment to improve the hole injection ability. A PEDOT:PSS solution is spin-coated on the substrate and annealed at 120 °C for 15 minutes to form a hole transport layer. Subsequently, a mixed solution of europium complex and electron transport material is deposited into the light-emitting layer by spin-coating, and the film thickness is controlled at 60 nm to optimize the optical and charge transport properties. The electron transport layer uses a metal oxide material and is annealed at 150 °C for 30 minutes to ensure its density and high electron mobility.

[0118] At the top of the OLED device, a metal cathode, such as aluminum (Al) or silver (Ag), is precisely deposited by vacuum evaporation to ensure good contact with the electron transport layer and improve the electron injection ability of the device. To enhance the durability of the device, a vacuum encapsulation process is adopted. A glass cover plate is covered on the OLED surface, and the periphery is sealed with ultraviolet curable glue to prevent the infiltration of air and moisture and improve the environmental stability of the device.

[0119] The present invention further enhances the durability of the device by constructing a multilayer inorganic / organic composite water and oxygen barrier film on the surface of the OLED device through atomic layer deposition (ALD) technology, effectively preventing the penetration of moisture and oxygen. The prepared barrier film has an oxygen transmission rate of less than 10 -6 g / m 2 ·day, ensuring the chemical stability of the europium complex and preventing the decrease in luminescence efficiency caused by oxidation or hydrolysis, thereby greatly improving the working life of the OLED device.

[0120] As Figure 3 shown, an organic europium complex based on a phenanthroline derivative and its electroluminescent device design method provided by an embodiment of the present invention include:

[0121] S201, through the derivative design module, specific substituents are introduced into the phenanthroline molecular structure to adjust its energy level to optimize the energy transfer efficiency to europium ions; the specific substituents include fluorine, methoxy, amino or carbonyl to enhance the intermolecular π-π stacking and the internal energy transfer of the molecule;

[0122] S202. Using phenanthroline derivatives as the main ligand in the europium complex core module and coordinating with europium ions to form a stable complex; introducing auxiliary ligands to regulate the thermal stability and photophysical properties of the complex;

[0123] S203. Emitting light, transporting electrons, and transporting holes through the multilayer device module;

[0124] S204. Using vacuum packaging combined with a water and oxygen barrier technology through the encapsulation module.

[0125] Through the derivative design module, specific substituents (such as fluorine, methoxy, amino, or carbonyl) are introduced into the phenanthroline molecular structure to regulate the electronic structure and energy level distribution of the molecule. These substituents can optimize the energy transfer efficiency from the phenanthroline derivative to the europium ion by adjusting the π-π stacking characteristics of the ligand and the intramolecular energy transfer path. In addition, the selection of these substituents can significantly improve the fluorescence quantum efficiency and the purity of the emission color of the complex, making it more suitable for high-performance electroluminescent devices.

[0126] The core design of the europium complex uses phenanthroline derivatives as the main ligand and coordinates with europium ions to form a highly stable metal complex structure. The complex further enhances the thermal stability by introducing auxiliary ligands (such as β-diketones or carboxylic acids) and adjusts the photophysical properties to meet the requirements of different devices. This design ensures the long-term operational stability of the complex in electroluminescent devices and simultaneously enhances the energy capture ability for the characteristic transitions of europium ions.

[0127] The device structure is optimized through the multilayer device module, including the combined design of the light-emitting layer, electron transport layer, and hole transport layer. The light-emitting layer is composed of an organic thin film based on the europium complex, ensuring high-efficiency electroluminescent performance during device operation. High-mobility materials are used for the electron transport layer and hole transport layer respectively to balance the injection and transport of charge carriers, reduce the diffusion of the exciton recombination region, and improve the luminescence efficiency and the photoelectric conversion efficiency of the device.

[0128] The device is protected by using vacuum packaging technology combined with a water and oxygen barrier material through the encapsulation module to prevent the erosion of water and oxygen on the europium complex and other organic layers. Low-temperature treatment is used during the encapsulation process to avoid damage to the performance of the organic layers at high temperatures and ensure the long-term stability of the device in a humid environment. This encapsulation scheme significantly improves the service life of the electroluminescent device and provides reliable technical support for practical applications.

[0129] Specific implementation of the present invention:

[0130] I. System structure design:

[0131] 1. Design of phenanthroline derivatives:

[0132] By introducing specific substituents (such as electron donor or acceptor groups) into the molecular structure of phenanthroline, its energy levels are adjusted to optimize the energy transfer efficiency to europium ions. Specific substituents include fluorine, methoxy, amino, or carbonyl groups to enhance intermolecular π-π stacking and intramolecular energy transfer.

[0133] 2. Core structure of europium complex:

[0134] Phenanthroline derivatives are used as the main ligands and coordinated with europium ions to form stable complexes.

[0135] Auxiliary ligands (such as β-diketone ligands) are introduced to regulate the thermal stability and photophysical properties of the complexes.

[0136] 3. Multilayer device structure:

[0137] Emission layer (EML): A mixture of europium complex and hole / electron transport materials forms the emission layer to improve charge injection efficiency.

[0138] Electron transport layer (ETL): Metal oxides with a lower work function (such as TiO 2 ) or other organic materials are used to enhance electron injection performance.

[0139] Hole transport layer (HTL): Hole transport materials with energy level matching (such as PEDOT:PSS) are introduced to optimize hole injection efficiency.

[0140] 4. Encapsulation system:

[0141] Through vacuum encapsulation combined with water and oxygen barrier technology, the working stability and lifespan of the device are improved.

[0142] II. Specific design:

[0143] 1. Design and preparation of phenanthroline derivatives

[0144] Objective: To improve the energy transfer efficiency to europium ions and enhance intermolecular π-π stacking to improve optoelectronic properties.

[0145] 1.1 Molecular design

[0146] Methoxy groups (electron donors) are introduced at the 2- and 9-positions of the phenanthroline molecule to increase the energy level of the ligand.

[0147] Fluorine or carbonyl groups (electron acceptors) are introduced at the 3- and 8-positions of phenanthroline to regulate intermolecular π-π stacking and energy transfer channels.

[0148] 1.2. Synthesis route

[0149] Using phenanthroline as the starting material, substituents are introduced by Friedel-Crafts reaction or Grignard reagents.

[0150] High-purity phenanthroline derivatives are obtained through purification techniques such as column chromatography and recrystallization.

[0151] 1.3. Energy level testing and optimization

[0152] The HOMO and LUMO energy levels of the ligand are determined using cyclic voltammetry (CV) and ultraviolet-visible absorption spectroscopy.

[0153] Select the phenanthroline derivative with the best energy level matching with the Eu(III) energy level as the ligand.

[0154] 2. Core structure design of europium complexes

[0155] Goal: Achieve efficient luminescence and thermal stability through a stable coordination structure.

[0156] 2.1. Complex preparation

[0157] Dissolve the designed phenanthroline derivative in anhydrous acetonitrile.

[0158] Add europium ion precursor (such as EuCl 3 ·6H 2 O) and β-diketone auxiliary ligand (such as trifluoroacetylacetone, TTA).

[0159] Stir and react at 80 °C for 2 hours, and slowly evaporate the solvent to precipitate the complex as crystals to form a stable europium complex.

[0160] 2.2. Structure characterization

[0161] Use elemental analysis, X-ray diffractometer, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) to characterize the coordination structure of the complex.

[0162] Use thermogravimetric analysis (TGA) to evaluate the thermal stability of the complex, and require the decomposition temperature to be higher than 250 °C.

[0163] 2.3. Luminescence performance testing

[0164] Test the photoluminescence spectrum and electroluminescence spectrum of the europium complex, and confirm the intensity and monochromaticity of its red emission peak at 612 nm.

[0165] Evaluate the luminescence efficiency through quantum yield testing to ensure that the efficiency is significantly higher than the existing technology.

[0166] 3. Realization of multilayer device structure

[0167] Goal: Construct an efficient light-emitting device and improve the overall performance by optimizing the interlayer energy level matching and charge injection performance.

[0168] 3.1. ITO Substrate Treatment

[0169] The ITO glass was ultrasonically cleaned with ethanol and isopropanol, and after drying, it was subjected to ultraviolet ozone treatment to enhance surface hydrophilicity and improve hole injection.

[0170] 3.2. Deposition of Hole Transport Layer (HTL)

[0171] The PEDOT:PSS solution was uniformly coated on the ITO surface, and a thin film was prepared by spin coating (2000 rpm, 60 seconds).

[0172] It was annealed at 120 °C for 15 minutes to form a uniform and flat hole transport layer.

[0173] 3.3. Deposition of Emission Layer (EML)

[0174] A mixed solution of europium complex and electron transport material was prepared (for example, europium complex and PVK were mixed in a ratio of 1:3 in chloroform).

[0175] The emission layer was deposited by spin coating, controlling the film thickness to be about 60 nm.

[0176] 3.4. Deposition of Electron Transport Layer (ETL)

[0177] An electron transport layer was prepared using a metal oxide material (such as TiO 2 nanoparticles), and it was uniformly coated on the emission layer.

[0178] It was annealed at 150 °C for 30 minutes to enhance the film density and electron transport performance.

[0179] 3.5. Deposition of Cathode Electrode

[0180] A metal cathode (such as aluminum, with a thickness of 100 nm) was deposited on the electron transport layer using vacuum evaporation.

[0181] 4. Implementation of Encapsulation System

[0182] Objective: To improve the working stability and lifespan of the device by combining vacuum encapsulation and a barrier film.

[0183] 4.1. Vacuum Encapsulation

[0184] The device surface was covered with a glass cover plate, and it was sealed around with ultraviolet curable glue.

[0185] The encapsulation was completed in a vacuum chamber to prevent air and moisture from infiltrating.

[0186] 4.2. Water and Oxygen Barrier Film

[0187] A multi-layer inorganic / organic composite water and oxygen barrier film is coated on the device surface, and the composite film is constructed by atomic layer deposition (ALD) technology.

[0188] The oxygen transmission rate of the barrier film needs to be lower than 10 -6 g / m 2 ·day to ensure the chemical stability of the europium complex during operation.

[0189] The synthesis of phenanthroline derivatives is the primary link in systematic optimization. Functional substituents (such as fluorine, methoxy, amino, or carbonyl) are introduced into the molecular structure of phenanthroline through Friedel-Crafts reaction or Grignard reagent reaction. These substituents regulate the molecular energy level distribution and electronic structure, enhancing the energy transfer efficiency with europium ions. Subsequently, the prepared phenanthroline derivatives are mixed with europium salts (such as EuCl3) in an anhydrous organic solvent (such as toluene or acetonitrile), and auxiliary ligands (such as trifluoroacetylacetone) are added to enhance the stability and luminescence performance of the complex. The coordination reaction is carried out under heating and stirring conditions, and finally, a europium complex with high thermal stability and excellent photophysical properties is formed.

[0190] Device fabrication begins with the cleaning and treatment of the ITO substrate. The cleaned ITO glass is coated with PEDOT:PSS by spin coating to form a uniform hole transport layer (HTL), improving the hole injection performance. The light-emitting layer uses a mixed solution of europium complex and auxiliary materials, which is spin-coated into a uniform thin film. The electron transport layer (ETL) deposits high-efficiency electron transport materials by vacuum evaporation or solution method to enhance the electron injection efficiency. Finally, an aluminum cathode is deposited on the top of the device by vacuum evaporation process to complete the construction of the basic structure of the electroluminescent device.

[0191] To extend the device lifespan, the device packaging adopts vacuum packaging technology, combined with UV curable glue for sealing treatment, and an additional water and oxygen barrier film is added to prevent moisture and oxygen from eroding the device structure. Special attention is paid to temperature control during the packaging process to ensure that the sensitive europium complex material will not degrade due to high temperature. Through efficient packaging, the stability of the device is greatly improved, providing a reliable guarantee for subsequent debugging and applications.

[0192] After the initial device fabrication is completed, the device performance is optimized by adjusting parameters such as the thickness of the light-emitting layer, the energy level matching of the hole and electron transport layers, and the electrode materials. At the same time, the influence of the doping concentration of different ligand derivatives and europium complexes on the luminescence performance is tested to ensure that the external quantum efficiency (EQE) reaches the optimal level. The optimized device can achieve high-brightness luminescence at a low operating voltage.

[0193] Through current-voltage-luminance (IVL) characteristic tests, the luminous efficiency and power efficiency of the device are measured at different voltages. The decay curve of luminance over time is recorded to evaluate the device lifetime. In the electrical performance tests, the injection balance of electrons and holes is further optimized by dynamically adjusting the voltage, thereby further enhancing the device stability and efficiency.

[0194] The optimized device has achieved significant improvements in luminous efficiency, stability, and monochromaticity. The combination of phenanthroline derivatives and europium complexes has increased the luminous efficiency by more than 30%, and the external quantum efficiency has reached 10%. At the same time, the thermal decomposition temperature has been increased to 260 °C, and the device lifetime has been extended to 1.5 times that of traditional technologies. The spin-coating process of the light-emitting layer simplifies the manufacturing process, reduces the production cost, and expands the application potential in the fields of high-end display devices, biomedical sensing, and agricultural lighting.

[0195] First, the specific application fields or related products of the present invention

[0196] The present invention can be widely applied to the field of high-resolution and high-color-reduction displays. By optimizing the luminescent properties of phenanthroline derivatives and europium complexes, it can provide red light-emitting materials with higher brightness and stronger monochromaticity for OLED display technology, significantly enhancing the color gamut and visual effects of displays.

[0197] Due to the improvement of luminous efficiency and stability, the technology of the present invention can be applied to a new generation of OLED lighting products, providing high-quality red light sources for special scenarios, such as medical lighting, plant growth lighting, and stage lighting.

[0198] The high-efficiency red light-emitting device of the present invention has good monochromaticity and narrow-band emission characteristics, and can be applied to red light signal transmitters in the field of optical communication, improving the performance and reliability of optical communication devices.

[0199] The high-efficiency and stable red light-emitting device can be used as a high-precision light source in optical sensors for detecting blood oxygen concentration, chemical substances, and biomarkers, etc.

[0200] By applying the optimized europium complex to laser display and projection systems, a more pure red light output can be achieved, meeting the requirements of high-end projection devices.

[0201] Second, the technical effects obtained in the embodiments of the present invention and related evidence

[0202] Through the structural optimization of phenanthroline derivatives and europium complexes, the present invention has improved the quantum yield of red light-emitting materials. Comparative experiments show that the quantum yield of the optimized europium complex has increased from 12% before optimization to more than 35%, significantly enhancing the luminous efficiency of the device.

[0203] After adopting encapsulation technologies (such as UV curable glue and water and oxygen barrier film), the lifespan of the device in high humidity and high temperature environments is extended to more than 5000 hours, while the unencapsulated device can only work stably for 800 hours under the same conditions. The test results show that the present invention has significant advantages in improving stability.

[0204] The optimized emission center wavelength of the europium complex is 612 nm, and the full width at half maximum of the spectrum is only 8 nm. Compared with traditional europium complexes (full width at half maximum above 20 nm), the monochromaticity is significantly improved. This result is verified by the test data of the spectrophotometer, proving that it can meet the requirements of high-precision display and optical communication.

[0205] By adjusting the thickness of the light-emitting layer and the concentration of the complex, the brightness of the device is increased from 500 cd / m 2 before optimization to 1200 cd / m 2 , and the brightness increase reaches 140%. In the experiment, it is found by debugging the voltage that the injection voltage only needs 3.5 V to reach the stable brightness state, reflecting the high injection performance of the device.

[0206] In the color gamut test, the red light-emitting device of the present invention covers more than 90% of the CIE 1931 color space, and the color rendering is significantly improved, showing obvious technological progress compared with ordinary europium complex light-emitting materials.

[0207] The synthesized phenanthroline derivative and europium complex in the present invention avoid using highly toxic solvents and heavy metal ions, and have good environmental compatibility. After third-party testing, no harmful substances are detected during the operation of the light-emitting device, meeting the environmental protection and safety standards.

[0208] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention.

Claims

1. An organic europium complex based on o-phenanthroline derivatives and an electroluminescent device thereof, characterized in that: include: Derivative design module, europium complex core module, multilayer device module, packaging module; A derivative design module, connected to the europium complex core module, is used to adjust the energy level of o-phenanthroline by introducing specific substituents into the molecular structure to optimize the efficiency of energy transfer to europium ions; specific substituents include fluorine, methoxy, amino or carbonyl to enhance intermolecular π-π stacking and intramolecular energy transfer; The europium complex core module is connected to the multilayer device module and is used to use o-phenanthroline derivatives as the main ligands and coordinate with europium ions to form a stable complex; auxiliary ligands are introduced to adjust the thermal stability and photophysical properties of the complex; A multilayer device module, connected to the packaging module, is used for light emission, electron transport, and hole transport; The packaging module is connected to the multi-layer device module and is used to combine water and oxygen barrier technology through vacuum packaging.

2. The organic europium complex based on o-phenanthroline derivative and the electroluminescent device thereof as claimed in claim 1, characterized in that: The derivative design module: (1) Molecular design Methoxy groups were introduced at the 2 and 9 positions of the o-phenanthroline molecule to increase the energy level of the ligand; Fluorine or carbonyl groups were introduced at the 3- and 8-positions of o-phenanthroline to regulate the π-π stacking and energy transfer channels between molecules; (2) Synthesis Path Using o-phenanthroline as a starting material, a substituent is introduced by using a Friedel-Crafts reaction or a Grignard reagent; High-purity o-phenanthroline derivatives are obtained through purification technology; (3) Energy level testing and optimization The HOMO and LUMO energy levels of the ligands were determined using cyclic voltammetry and UV-visible absorption spectroscopy; A phenanthroline derivative whose energy level best matches the energy level of the europium ion 3+ is selected as the ligand.

3. The organic europium complex based on o-phenanthroline derivative and the electroluminescent device thereof as claimed in claim 1, characterized in that: The europium complex core module: 1) Preparation of complex The designed o-phenanthroline derivative was dissolved in anhydrous acetonitrile; adding a europium ion precursor and a β-diketone auxiliary ligand; Stir the reaction at 80°C for 2 hours, and slowly evaporate the solvent to allow the complex to precipitate in the form of crystals to form a stable europium complex; 2) Structural characterization The coordination structure of the complex was characterized by elemental analysis, X-ray diffractometer, infrared spectroscopy and nuclear magnetic resonance; The thermal stability of the complex was evaluated using thermogravimetric analysis, requiring the decomposition temperature to be above 250 °C; 3) Luminous performance test The photoluminescence and electroluminescence spectra of the europium complex were tested to confirm the intensity and monochromaticity of its red light emission peak at 612nm; The luminous efficiency is evaluated by quantum yield testing, ensuring that the efficiency is significantly higher than existing technologies.

4. The organic europium complex based on o-phenanthroline derivative and the electroluminescent device thereof as claimed in claim 1, characterized in that: The multi-layer device module: (1) ITO substrate processing The ITO glass was ultrasonically cleaned with ethanol and isopropanol, and then dried and treated with UV-ozone to enhance surface hydrophilicity and improve hole injection; (2) Deposition of hole transport layer The PEDOT:PSS solution was uniformly coated on the ITO surface, and the thin film was prepared by spin coating; Annealing at 120°C for 15 minutes to form a uniform and flat hole transport layer; (3) Deposition of the light-emitting layer preparing a mixed solution of a europium complex and an electron transport material; The light-emitting layer is deposited by spin coating, and the film thickness is controlled to be around 60nm; (4) Deposition of electron transport layer An electron transport layer is prepared using a metal oxide material and is uniformly coated on the light-emitting layer; Annealing at 150°C for 30 minutes to enhance the film density and electron transport performance; (5) Deposition of cathode electrode A metal cathode is deposited on the electron transport layer using vacuum evaporation.

5. The organic europium complex based on o-phenanthroline derivative and the electroluminescent device thereof as claimed in claim 1, characterized in that: The encapsulation module: 1) Vacuum packaging Cover the device surface with a glass cover plate and seal it with UV curing glue on all sides; The packaging is completed in a vacuum chamber to prevent air and moisture from penetrating; 2) Water and oxygen barrier membrane.

6. The organic europium complex based on o-phenanthroline derivative and the electroluminescent device thereof as claimed in claim 5, characterized in that: The water oxygen barrier membrane: Coating a multilayer inorganic / organic composite water and oxygen barrier film on the device surface, and constructing the composite film using atomic layer deposition technology; The oxygen permeability of the barrier film should be less than 10 -6 g / m 2 ·day, to ensure the chemical stability of the europium complex during operation.

7. A method for designing an organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof, which implements the organic europium complex based on a phenanthroline derivative and an electroluminescent device thereof as claimed in any one of claims 1 to 6, characterized in that: The organic europium complex based on o-phenanthroline derivative and the design method of the electroluminescent device thereof include: Step 1, introducing specific substituents into the molecular structure of o-phenanthroline through a derivative design module to adjust its energy level to optimize the efficiency of energy transfer to europium ions; specific substituents include fluorine, methoxy, amino or carbonyl to enhance intermolecular π-π stacking and intramolecular energy transfer; Step 2, using a phenanthroline derivative as a main ligand through a europium complex core module, and coordinating with europium ions to form a stable complex; introducing an auxiliary ligand to adjust the thermal stability and photophysical properties of the complex; Step 3, light emission, electron transport, and hole transport through a multilayer device module; Step 4: Use vacuum packaging combined with water and oxygen barrier technology to package the module.

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