Preparation Of Polymer Electrolyte Material Based On FOLED Packaging And Study On The Properties Of Ultrasonic-Assisted Electrostatic Bonding

Flexible Organic Light Emitting Diodes（FOLEDs）represent a new generation of display and lighting devices,boasting advantages such as flexibility,rapid response,low power consumption,and exceptional luminescence performance.They have found widespread use in various types of display devices and hold a broad sustainable development market.However,their industrialization currently faces several challenges,with the main factors hindering their development being their lifespan,stability,and high cost.Packaging is a critical step in FOLED device manufacturing,and its quality directly affects the stability and lifespan of the devices.Advanced packaging technologies are urgently needed to improve device stability and lifespan,enhance performance,and increase market share.Electrostatic bonding offers high packaging efficiency,excellent sealing,low cost,and easy connection of heterogeneous materials.Based on this research background,the main content of this study is as follows:A self-designed ultrasonic-assisted electrostatic bonding system and a three-layer edge-stacked co-anode packaging structure suitable for FOLEDs have been developed.Through blending and adding inorganic fillers for modification,a series of high-performance PEO-LiClO₄-LiTFSI,PEO-LiClO₄-LiTFSI-SiO₂,and PEO-PUEE flexible polymer electrolyte thin film packaging materials suitable for ultrasonic-assisted electrostatic bonding have been prepared using the"liquid-phase mixing-roll-to-film-thermoforming"process.The effects of modification additives and their content on the properties of polymer electrolytes have been studied through various analytical characterization methods,and their underlying mechanisms have been extensively analyzed and discussed.Simultaneously,the prepared flexible polymer electrolyte thin film packaging materials have been bonded to aluminum foil using ultrasonic-assisted electrostatic bonding experiments,studying the bonding current’s variation over time during the bonding process under different ultrasonic amplitudes and bonding voltages.The bonding quality has been analyzed,and the optimal process parameters have been determined.A microwave non-destructive testing system for interface defects in ultrasonic-assisted electrostatic bonding has been established based on a microwave vector network analyzer.By conducting ultrasonic-assisted electrostatic bonding experiments on bonding materials preset with different defect types and performing microwave non-destructive testing on the bonding interface defects,the detection results of each defective sample have been analyzed and compared with actual defects to verify the feasibility of microwave detection technology for actual defect detection in the bonding interface of polymer electrolyte ultrasonic-assisted electrostatic bonding packaging.The main research conclusions of this thesis are as follows:（1）The addition of LiTFSI improves the ionic conductivity of PEO-LiClO₄-LiTFSI while slightly reducing its mechanical properties.When the LiTFSI content is 20 wt.%,the highest room temperature ionic conductivity is 4.48x10^-5S cm^-1,and the lowest material yield strength is 33.44 MPa.This is due to the different solubility and coordination capabilities of LiTFSI and LiClO₄.The addition of LiTFSI disrupts the original regular structure of PEO to a greater extent,increases the amorphous region,reduces crystallinity,and simultaneously reduces the coordination of Li⁺with PEO in LiClO₄,releasing more Li⁺.（2）The addition of SiO₂improves the ionic conductivity,overall thermal stability,and mechanical properties of PEO-LiClO₄-LiTFSI-SiO₂.When the SiO₂content is 10 wt.%,the highest room temperature ionic conductivity is 4.83x10^-5S cm^-1.When the SiO₂content is 15 wt.%,the maximum material yield strength is 53.68 MPa.This is due to the uniformly dispersed SiO₂within the matrix,which serves as a scaffold to strengthen the PEO molecular chains,inhibiting the intermolecular bonding of PEO chains,reducing the overall crystallinity of the system,and increasing the ion transport channels due to SiO₂’s large specific surface area.（3）The interaction between PEO and polyurethane matrix allows LiClO₄and LiTFSI to dissolve more in the matrix,reducing the glass transition temperature of the composite material,improving the ionic conductivity of the material,and enhancing its mechanical properties.When the PEO electrolyte content is 20wt.%,the maximum room temperature ionic conductivity is 5.5x10^-5S cm^-1.（4）As the bonding voltage and ultrasonic amplitude increase,the peak current during the bonding process also increases.A certain width and dense bonding layer forms between the polymer electrolyte and the aluminum foil.When the LiTFSI content is 20 wt.%,the PEO-LiClO₄-LiTFSI/Al bonding process has the highest peak current and the highest room temperature tensile strength of the bonding interface at 1.68 MPa.When the SiO₂content is 10 wt.%,the PEO-LiClO₄-LiTFSI-SiO₂/Al bonding process has the highest peak current and the highest room temperature tensile strength of the bonding interface at 7.73MPa.When the PEO-LiClO₄-LiTFSI-SiO₂content is 20 wt.%,the PEO-PUEE/Al bonding process has the highest peak current and the highest room temperature tensile strength of the bonding interface at 1.81 MPa.（5）The microwave detection results obtained by the microwave non-destructive testing system for bonding interface defects are in good agreement with the destructive test results.This confirms the feasibility of microwave detection technology for the actual defect detection of the bonding interface in polymer electrolyte ultrasonic-assisted electrostatic bonding packaging.