Preparation And Luminescence Properties Of Eu³⁺ Doped Inorganic/organic Hybrid Fluorescent Fiber

Inorganic/organic hybrid fluorescent fibers have been widely concerned as a potential light source materials for flexible LED devices due to its excellent performance of low cost,flexibility,portability,and durability.Red LEDs become the main component of plant light supplement lamp due to its emission wavelength at 600-700 nm,being the greatest contribution to plant light and action.Red rare earth Eu inorganic phosphors become the preferred materials because of its wide emission range in the red region.However,inorganic Eu red phosphors are easy to agglomeration,poor dispersity and difficult to form films,which limits its application.Based on this,europium inorganic phosphor was modified first in this paper,and endow its polymerization activity,copolymerize to prepare inorganic/organic hybrid phosphors with methyl methacrylate（MMA）monomer.Then,flexible inorganic/organic hybrid fluorescence fibers will be spun by electrostatic spinning technology.Red light flexible LED devices will be fabricated employing the flexible inorganic/organic hybrid fluorescence fibers.The LED devices have potential application in terms of plant fill light.The specific research contents and results are as follows:（1）The red phosphor Ba₃ScB₃O₉:Eu³⁺was prepared by a two-step high temperature solid state method.The modified red phosphor VTES@Ba₃ScB₃O₉:0.05Eu³⁺was prepared by surface modification of the phosphor with vinyl trethoxysilane（VTES）.Infrared spectroscopy,XRD,fluorescence spectroscopy,SEM and XPS were used to characterize the structure and properties of the phosphor before and after modification.The results confirm that the silane coupling agent is bonded to the surface of the phosphor through chemical bonds.Modified phosphor VTES@Ba₃ScB₃O₉:0.05Eu³⁺average particle size decrease,agglomeration phenomenon significantly is weakened.The fluorescent films were prepared by doping the phosphor powder with polymethyl methacrylate before and after modification.The hydrophobicity and dispersion of phosphor powder in organic phase are obviously enhanced.The LED device encapsulated with modified phosphor can inhibit the non-radiative transition and PL quenching phenomena of phosphor,and the luminance of the LED device encapsulated with modified phosphor is 1.26 times of that of the LED device without modified fluorescent films.The modified red phosphor LED device has potential application in the field of indoor plant lighting light therapy.（2）The bonded inorganic/organic hybrid phosphors PMMA-VTES@Ba₃ScB₃O₉:0.05Eu³⁺was obtained by copolymerization of VTES@Ba₃ScB₃O₉:0.05Eu³⁺and MMA monomer to obtain PMMA-VTES@Ba₃ScB₃O₉:0.05Eu³⁺.The morphology of PMMA-VTES@Ba₃ScB₃O₉:0.05Eu³⁺fluorescence fibers was regulated by optimizing the molecular weight of the polymer,the concentration of the polymer solution and the electrospinning solution parameters of the conductive salt,and the relationship between the fibers morphology and the luminescence properties was studied.The results show that the fibers diameter decrease with the decrease of molecular weight,and the fluorescence intensity reach the highest when the molecular weight is 29123.The fibers diameter and fluorescence intensity increase with the increase of the concentration of spinning solution,and the morphology is best when the concentration is 30%.With the addition of conductive salt,the fibers diameter is small and uniform,and the fluorescence intensity increases first and then decreases with the increase of conductive salt content,but the intensity is generally lower than that of the fluorescence fibers without conductive salt.The initial decomposition temperature of fluorescent fibers increase from 205℃to 235℃.PMMA-VTES@Ba₃ScB₃O₉:0.05Eu³⁺inorganic/organic hybrid red fibers with stable thermal performance and excellent luminescence performance were obtained.（3）In order to investigate the practical application value of PMMA-VTES@Ba₃ScB₃O₉:0.05Eu³⁺fluorescent fibers membrane,the acid and alkali resistance and water resistance of the fibers membrane were studied,and the red LED fiber membrane devices and anti-counterfeiting devices were prepared,and their luminescence and anti-counterfeiting properties were studied.The results show that the fiber films have a good tolerance in alkaline solution and water,the fibers morphology and luminescence properties keep stable.The acid resistance is the worst because the fibers almost completely decompose under acidic environment,resulting in the loss of fluorescence properties.By comparing the performance of polymer phosphors and fibers LED devices,the brightness of fibers LED device is 1.37 times that of film LED devices,indicating the brightness of red LED device improves after fibrosis.The average life of fluorescent fiber is 6.033 ms.Compared with the corresponding phosphors,the effect of fibrotic on fluorescence lifetime is very small.The fluorescent fibers were printed on the non-woven fabric.Under the irradiation of 254 nm light source,the non-woven fabric presents a well-preserved logo pattern,indicating that the fibers have potential applications in anti-counterfeiting and light-emitting fabrics.