Investigation of e-h Trapping Efficiency in Eu3+ Doped YPO4 Using VUV Spectroscopy

Absorption of Vacuum Ultraviolet (VUV) radiation creates excited electron – hole (e – h) pairs in phosphors that can either be trapped by bulk defect states, surface defects, Ln3+ activators, or recombine by host emission. The fraction of e – h captured by Ln3+ is defined as the transfer efficiency, nt. Host – to – activator energy transfer efficiencies were determined for micro- and nano-crystalline Y1-xPO4:Eux3+ (0.0025 \u3c x \u3c 0.10) using excitation and reflectance spectroscopy. For YBO3:Eu3+ nano – particles, more e – h pairs are lost to the surface relative to the corresponding micron particles. Our work on YPO4:Eu3+ nano – particles reveals a similar result. However, for both compounds, no conclusion could be made about the effect of particle size on the bulk transport of e – h pairs