Erbium–Ytterbium Upconversion in Polyvinyl Chloride Films

Abstract

We have prepared a series of polyvinyl chloride–yttrium oxysulfide composites doped with ytterbium and erbium ions and measured their upconversion photoluminescence spectra and volume resistivity. The results demonstrate that the green photoluminescence intensity in the composites is considerably higher than that in yttrium oxysulfide doped with erbium and ytterbium. The resistivity of the composites drops by eight orders of magnitude on heating. Besides, with increasing erbium–ytterbium ion pair concentration, the upconversion photoluminescence intensity in the red and green spectral regions rises, and additional photoluminescence peaks emerge, two in the green and one in the red, owing to the Stark splitting of the erbium terms under the effect of the chlorine present in the polyvinyl chloride. On heating, the PVC–Y₂O₂S:Yb³⁺/Er³⁺ composite passes into a semiconducting state.