Optimizing Red Emitting Near-Infrared to Visible Upconversion Fluorescent Nanoparticles by Doping Non-Lanthanide Ion

Abstract

Lanthanide doped upconverting materials in recent times have increasingly gathered attention in multitudinous cutting-edge applications including biological imaging, medical diagnosis and photodynamic therapy, solar cells, anticounterfeiting, photocatalysis, color display so on, which are attributable to their brilliant merits of high chemical and optical stability, narrow multi-band emissions, deep tissue penetration, long fluorescence lifetime and little biological toxicity. The NIR light is advantageous for bioimaging because it does not induce auto-fluorescence from biomolecules and it makes clear fluorescence imaging with a high signal-to-noise ratio possible. Compared with blue- and greenemitting UCNPs, red-emitting UCNPs are beneficial for in vivo imaging application because red light lies in the optically transparent window of a biological system. Indeed, red light can penetrate deeper into the tissue than green light. In this work different methods can be adopted for the synthesis of red-upconverting nanoparticles. Also study on enhanced emission profile on incorporation of non-lanthanide ion Li+ on characterization of photoluminescence and the crystalline material was proposed. The detailed mechanism behind the intensification of the emission profile is to perturbation of crystal field symmetry of crystal lattice to be investigated by lattice strain analysis.