Up-conversion of 980 nm light into white light from sol-gel derived thin film made with new combinations of LaF3:Ln3+ nanoparticles

Abstract

White light was generated from SiO2 and ZrO2 sol-gel thin films made with four different combinations of lanthanide-doped nanoparticles. A 33-fold increase in the white light emission intensity was observed with the Commission Internationale de I'Eclairage (CIE) co-ordinates of 0.30, 0.34 from a silica thin film made with combination 2 (Yb/Tm and Yb/Er) nanoparticles when compared to our previous thin film. An absolute quantum yield of 0.1% for the green Er3+ emissions in this sample was determined by an absolute method using an integrating sphere. The quantum yield is defined as photons emitted divided by photons absorbed, so it runs from 0 to 100% for one-photon processes, from 0 to 50% for two-photon processes, etc. Similarly, silica thin films made with combination 1 (Yb/Tm, Yb/Ho, and Yb/Er), combination 3 (Yb/Tm, Yb/Tb, and Yb/Er) and combination 4 (Yb/Tm, Yb/Tb, and Yb/Eu) nanoparticles also produced white light with higher efficiency when compared to our previous thin film. ZrO2 thin films made with these new combinations of nanoparticles also showed similar increases in the efficiency of white light.