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

Journal of Luminescence, April 2019, 208

(Sr,Ca)AlSiN3:Eu²⁺ phosphors have been widely used in phosphor-converted white light emitting diodes. Herein, we reported the strong red persistent luminescence in (Sr,Ca)AlSiN3:Eu²⁺ under UV light excitation. The Sr0.8Ca0.2AlSiN3:0.15% Eu²⁺ 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/m² threshold value. A new persistent luminescence mechanism, which is different to that of SrAl2O4:Eu²⁺,Dy³⁺, was proposed by comparing the thermoluminescence excitation spectrum (TLES) and the photoluminescence excitation spectrum (PLES) of Sr0.8Ca0.2AlSiN3:0.15% Eu²⁺. The electrons are directly excited from 4f ground states to the conduction band or from valence band to conduction band in (Sr,Ca)AlSiN3:Eu²⁺; while, in SrAl2O4:Eu²⁺,Dy³⁺, they are first excited to 5d level and then stimulated thermal process to the conduction band. The effect of Eu²⁺ concentration on red persistent luminescence in (Sr,Ca)AlSiN3:Eu²⁺ were discussed. The proposed mechanism of persistent luminescence can help us to design and find new persistent luminescence materials.

Luminescence Tuning, Thermal Quenching, and Electronic Structure of Narrow-Band Red-Emitting Nitride Phosphors applications

Inorg. Chem., 2017, 56, 19, 11837–11844.

Exploring high-performance narrow-band red-emitting phosphor is an important challenge for improving white light LEDs. Here, on the basis of three interesting nitride phosphors with similar vierer rings framework structure, two phosphor series, Eu2+-doped Sr(LiAl)1–xMg2xAl2N4 and Sr(LiAl3)1–y(Mg3Si)yN4 (xy = 0–1), are successfully synthesized by a solid state reaction. They show narrow-band red emission with tunable emission peaks from 614 to 658 nm and 607 to 663 nm. The varying luminescence behaviors with composition and structure are discussed based on centroid shift, crystal field splitting and Stokes shift. On the basis of experimental data, we construct the host referred binding energy (HRBE) and vacuum referred binding energy (VRBE) schemes of divalent/trivalent lanthanide-doped end-member compounds, and further give thermal quenching mechanism of these series phosphors.