Trap distribution tailoring guided design of super-long-persistent phosphor Ba2SiO4:Eu2+,Ho3+ and photostimulable luminescence for optical information storage

Abstract

Here, we report a novel long-persistent luminescence (LPL) phosphor, Ba₂SiO₄:Eu²⁺,Ho³⁺. The crystal structure, photoluminescence, photoluminescence excitation and LPL decay behaviors were studied systematically. The developed LPL phosphor Ba₂SiO₄:Eu²⁺,Ho³⁺ shows super-LPL, which remains above 2.97 mcd m⁻² even 24 h after the removal of UV irradiation source. The outstanding LPL performance is mainly derived from the tailoring of trap distribution via Ho³⁺ co-doping. 15 days after UV irradiation, the sample still shows observable green luminescence by 980 nm stimulation. By means of photostimulated luminescence (PSL), excitation duration, decay duration and excitation temperature dependent thermoluminescence spectra, the continuous trap distribution, trap distribution modulation and dynamics of electron motion are characterized. The role of co-dopant Ho³⁺ serving as electron traps and the tailoring of trap distribution are revealed. The fabrication of Ba₂SiO₄:Eu²⁺,Ho³⁺ phosphor film allows optical information write-in after passing UV light through a photomask (projection printing method) and then the stored information is read out by thermal stimulation or 980 nm photostimulation, which holds great promise for optical information storage. Moreover, combined with the experimental and DFT calculation results, a tentative schematic diagram is proposed for the illustration of LPL and PSL mechanism in Ba₂SiO₄:Eu²⁺,Ho³⁺.