BaF 2 and AlF 3 were used for the preparation of BaAl 2 S 4 :Eu thin-film phosphors. The blue emission with a peak at 470 nm was obtained particularly because the process temperature was not sufficient for obtaining a peak at 470 nm in the case of a conventional technique. The intensity of the blue emission from BaAl 2 S 4 :Eu phosphors prepared using fluoride compounds was higher than that of phosphors prepared without fluoride compounds, and the appropriate annealing temperature decreased during the preparation process. It is considered that BaF 2 and AlF 3 enhanced the reaction of starting materials and accelerated the crystallization of BaAl 2 S 4 . The crystallinity and mean crystal particle size of BaAl 2 S 4 :Eu phosphors prepared using fluoride compounds were improved. This is due to the fluoride compounds effectively acting as flux materials.