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 160 nm 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 8.5 eV and 7.5 eV, 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 7.75 eV. The band gap energy of BaLiF3 is estimated from its absorption spectrum to be around 8.41 eV. Results suggest the possibility of developing VUV solid-state devices including light emitting diodes.