Synthesis And Luminescence Enhancement Studies Of 808NM Excited Upconversion Luminescent Materials

NaYF4 is an important upconversion luminescent material.Due to its unique and excellent up-conversion luminescence properties and good biocompatibility,NaYF4 has broad applications in solar cells,three-dimensional imaging and bioimaging.In recent years,the application of NaYF4 luminescent materials in the field of biomedical imaging has been particularly rapidly developed,but owing to the limitations of the material itself and some characteristics of biological tissue,it has two limitations,one is the problem of lower luminous efficiency,and the other is that the excitation wavelength of the upconversion luminescent material is generally located at 980 nm,yet the larger thermal absorption cross section of the water molecules were at 980 nm,which results in a thermal effect.In this paper,these two defects as a breakthrough point to start the study to a certain extent,solve the above two problems,the specific work done for the following areas:(1)The Nd3+ sensitized NaYF4:Yb3+,Er3+,Nd3+ upconverting luminescent materials were prepared by high temperature thermal decomposition of trifluoroacetate.The excitation wavelength of the upconverting nanoparticles was realized by the principle of energy cascade transfer.The excitation wavelength Regulated by 980nm to 808nm.(2)Ag nanoparticles were prepared by sodium citrate reduction method.Ag@SiO2 nanoparticles with core-shell structure were prepared by hydrolyzing tetraethylorthosilicate with Ag nanoparticles as the core.The luminescence intensity of Ag@SiO2 nanoparticles was enhanced by mixing NaYF4:Yb3+,Er3+ and Nd3+upconverting luminescent nanoparticles.(3)IR806 dye molecules were synthesized using IR780 dye molecules.The IR806 dye molecules were used to sensitize Ag@SiO2-enhanced NaYF4:Yb3+,Er3+,Nd3+ upconversion luminescent nanoparticles.Utilizing the characteristics of the large absorption cross section of the dye molecule and the energy transfer between the dye molecule and the up-conversion nano-particles,the luminous efficiency is further improved.The results show that:(1)when the Ag@SiO2 nanoparticles are only upconverted to the upconverted nanoparticles,the luminescent intensity is the strongest when the mass ratio of Ag@SiO2 nanoparticles is 1:5017;(2)With the increase of the concentration of IR806 dye molecules,The luminescence of NaYF4:Yb3+,Er3+ and Nd3+ upconverting nanoparticles is the first to increase and then decrease.(3)The luminescent efficiency of Ag@SiO2 nanoparticles,IR806 dye molecules and NaYF4:Yb3+,Er3+,Nd3+ upconverting nanoparticles is about 23 times higher than that of pure NaYF4:Yb3+,Er3+,Nd3+ upconverting nanoparticles,which has achieved the common enhancement of both excitation and emission.