Perovskite fluoride crystals as light emitting materials in vacuum ultraviolet region

•Time-resolved spectroscopy of fluoride crystals are carried out by EUV-FEL excitation.•Fluorescence at 160nm that is not reported in previous paper was observed from BaLiF.•Fluoride composition can be engineered to develop LED in the VUV region. Vacuum-ultraviolet (VUV) fluorescence from KMgF3 and BaLiF3 crystals excited by an extreme ultraviolet free electron laser (EUV-FEL) with 61-nm emission wavelength is studied. Cross-luminescence (CL) peaks at 8.5eV and 7.5eV, due to an electron from the valence band recombining with a hole in the F2p core band edge are observed in KMgF3. On the other hand, BaLiF3 exhibited a fluorescence peak at 7.75eV. The band gap energy of BaLiF3 is estimated from its absorption spectrum to be around 8.41eV. Results suggest the possibility of developing VUV solid-state devices including light emitting diodes.