Preparation Of Complex Of Graphene Quantum Dots And Metal Organic Frames And Its Application In Optical Field

Semiconductor light-emitting diode(LED)lighting has the advantages of long service life,energy conservation,environmental protection,and will gradually replace the traditional high energy consumption,short life of the incandescent lamp and fluorescent lamp,become the mainstream lighting technology in the future.Joining phosphor on the LED chip is the main way to realize the white light LED lighting,but the traditional phosphor is mostly rare earth compounds,not only the high cost,non-renewable,but also the pollution to the environment.New type of low cost,environment friendly graphene quantum dot fluorescent material has good fluorescence performance and ability to resist photobleaching,but due to its fluorescence quenching will happen after curing which restricting the application in the LED chip.This paper explores the application of graphene quantum dot phosphors through effective cladding technology in white LED devices to solve the curing fluorescence quenching problem.Mainly through the graphene quantum dots encapsulated in the metal organic framework,after curing made LED devices,quantum dots can keep original good fluorescence properties,showed good thermal stability and white light illumination.At the same time,the fluorescence composite is optimized to have good dispersion stability in aqueous solution and applied to cell imaging.The main content includes the following aspects: 1.Elucidation of the preparation methods of graphene quantum dot and metal organic framework,the main classification and the types of complexes of metal organic framework and their application prospects in some fields.Then introducing the history development and characteristics of white LED and the main types,device structure and working principle of fluorescent powder conversion white LED.2.Preparation of yellow fluorescent GQD@ZIF-8 solid powder.Since yellow phosphor can be applied to blue ray chip for forming white LED devices,In this paper,we use methanol as solvent and stir with sulfonic group quantum dots quickly at room temperature to prepare yellow fluorescent GQD@ZIF-8 composite materials.The size diameter of GQD@ZIF-8 is 40-50 nm,and the emission peak is located at 480 nm with the fluorescence decay time of 12.73 ns.It has certain fluorescence dependence and it will appeared shifted towards the longer wavelength side with the increase of the excitation wavelength,and the material will maintain stable fluorescence intensity for a long time.3.The application of white LED devices with yellow fluorescent GQD@ZIF-8 composites materials.The yellow fluorescent GQD@ZIF-8 composite materials are applied to white LED devices with the blue LED chip througth the processes of pulping,coating,drying and packaging.To improve the parameters of white LED,we change the quality of GQD@ZIF-8 and the input current size.The study found that when the mass of GQD@ZIF-8 is 200 mg and the current is 30 mA,the white LED with the optimal color coordinate of(0.3439,0.3268),the color index is up to 84.6,the spectral coverage range is 420-800 nm,color temperature value is 4952 K,lumen efficiency is 8.5 lm/W and the thermal stability attenuation rate is only 13.7%.4.Preparation of water-soluble cyan fluorescent GQD@ZIF-8@PVP.We improve the synthesis conditions to successfully prepare the composite.Water is substituted for methanol as the solvent,and polyvinylpyrrolidone is added as an adjuvant.The fluorescence performance is found that the emission peak is located at 480 nm with fluorescence dependence,and fluorescence quantum yield is 26.1%,the fluorescence decay time is 2.24 ns.The composite is initially used as a biofluorescence probe in cell imaging.