Photoluminescent properties of BaF2 scintillator-polystyrene composite films under vacuum ultraviolet radiation

•Optical absorption and photoluminescence in BaF2-polystyrene composite were analyzed.•Efficiency method to indirectly estimate the fraction of light absorbed was proposed.•BaF2 self-trapped excitons incorporated into the polystyrene are excited at 5.6 eV.•The lower exciton formation energy was attributed to a synergistic effect.•Tunable emission intensity and color were presented by the composites.