The Effect of Needle Diameter on Optical Properties and Morphological Structure of La203-PVA Phosphor Nanofibers Prepared by Electrospinning Method

摘要

Lanthanum Oxide-Polyvinyl alcohol (La_2O_3-PVA) phosphor nanofibers were prepared by electrospinning and investigation of the effect of needle diameter on the optical properties and morphological structure at the nanofibers was carried out. The average diameter of phosphor nanofibers have been evaluated for five different needle diameters. The resulting phosphor nanofibers were observed and analyzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Ultraviolet-visible Spectroscopy (UV-Vis) and HPC-2 Lightsource Colorimeter. The La_2O_3-PVA phosphor nanofibers were used in light down-conversion of UV light (365 nm) for the white light-emitting diode (WLED) application. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for different phosphor nanofibers with different sizes of needle diameter (0.45,0.55,0.65,0.75,1.1) mm. The results revealed that the phosphor nanofibers formed by needle diameter of 0.65 mm places macromolecule in a better order and the average diameter increase from 40.08 nm to 87.27 nm after annealing followed by increasing in atomic percentage of lanthanum. The energy gap of chosen phosphor nanofibers is 3.5365 eV. An optimum color rendering index (CRI) value of 70.20 is obtained. The white phosphor exhibited CIE values of 0.3536, 0.407 and CCT of 4890 K.