Enhanced photoluminescence and phosphorescence properties of red CaAlSiN3:Eu2+ phosphor via simultaneous UV-NIR stimulation

Abstract

Red-emitting CaAlSiN₃:Eu²⁺ phosphors with different doping contents have been synthesized by solid-state reaction using calcium hydride as a calcium source. The emergence of persistent luminescence in CaAlSiN₃:Eu²⁺ was originated from electron traps introduced by the partial substitutions of O in N sites to form positive trap levels at low Eu²⁺ concentration. The broad thermoluminescence emission bands indicated multiple trap levels, in which the shallow traps were mainly responsible for the red persistent luminescence; besides, the deep trap electrons could be efficiently released under extra NIR (980 nm) stimulation, resulting in enhanced photoluminescence and phosphorescence. It is expected that the enhanced emission under UV-NIR simultaneous excitation may be a promising technique to investigate the trap distributions in optical energy storage materials.