Eu3+ activated BaF2 nanostructured thin films: fabrication and a combined experimental and computational study of the energy conversion process

Abstract

Significant work has recently focused on developing novel materials suitable for solar technologies with better conversion efficiencies, while maintaining low costs. BaF2 has been investigated as a fluoride host for doping with luminescent ions for energy conversion processes in photovoltaic cells. This work employed a metal-organic chemical vapor deposition technique to prepare nanostructured europium-doped BaF2 thin films on silicon and quartz substrates. Samples have been fabricated by varying the deposition temperature from 300 to 600 °C in order to examine how temperature affects the structure, morphology, and luminescence of Eu-doped BaF2 thin films. A multicomponent combination of fluorinated β-diketonate metal-organic precursors of barium and europium, Ba(hfa)2·tetraglyme and Eu(hfa)3·diglyme, in an appropriate molar ratio, is employed to fabricate BaF2 based thin films. These precursors serve as a single molten source by delivering all the elements required (Ba, Eu, and F) for forming the Eu-doped BaF2 phase due to the similar nature of the ligands. On silicon substrates, preliminary deposition tests have been carried out to confirm the purity, homogeneity, and appropriate stoichiometry of films. The obtained results pave the way for the production of BaF2 thin films doped with lanthanide ions, particularly interesting for their up-conversion (UC), down-conversion (DC), and down-shifting (DS) properties.