The red persistent luminescence of (Sr,Ca)AlSiN3:Eu2+ and mechanism different to SrAl2O4:Eu2+,Dy3+

Abstract (Sr,Ca)AlSiN 3 :Eu 2+ phosphors have been widely used in phosphor-converted white light emitting diodes. Herein, we reported the strong red persistent luminescence in (Sr,Ca)AlSiN 3 :Eu 2+ under UV light excitation. The Sr 0.8 Ca 0.2 AlSiN 3 :0.15% Eu 2+ shows the strongest red persistent luminescence with a peak emission wavelength at ~628 nm and a persistent time of ~9600 s at the 0.32 mcd/m 2 threshold value. A new persistent luminescence mechanism, which is different to that of SrAl 2 O 4 :Eu 2+ ,Dy 3+ , was proposed by comparing the thermoluminescence excitation spectrum (TLES) and the photoluminescence excitation spectrum (PLES) of Sr 0.8 Ca 0.2 AlSiN 3 :0.15% Eu 2+ . The electrons are directly excited from 4 f ground states to the conduction band or from valence band to conduction band in (Sr,Ca)AlSiN 3 :Eu 2+ ; while, in SrAl 2 O 4 :Eu 2+ ,Dy 3+ , they are first excited to 5d level and then stimulated thermal process to the conduction band. The effect of Eu 2+ concentration on red persistent luminescence in (Sr,Ca)AlSiN 3 :Eu 2+ were discussed. The proposed mechanism of persistent luminescence can help us to design and find new persistent luminescence materials.