Spectroscopic investigation of Sr_1-xCa_xLiAl₃N₄:Eu²⁺ phosphor involving structural characterization, luminescence...

The advancement of backlighting displays is dependent on the development of efficient narrow-band red phosphors. However, challenges such as low thermal stability and insufficient quantum efficiency restrict their widespread use in high-power LEDs. This study reports the synthesis of various solid solutions of Sr_1-xCa_xLiAl₃N₄:Eu²⁺ (0 ≤ x ≤ 0.8) (SCLAN:Eu²⁺) through the partial substitution of strontium with calcium using a low gas pressure sintering method (0.3 MPa). The intentional introduction of cation disorder by substituting Sr with Ca significantly enhances quantum efficiency and suppresses thermal quenching. Comprehensive analysis of SCLAN:Eu²⁺ phosphors includes their structural characteristics and luminescence properties, as well as the synthesis and thermal quenching of white-light-emitting diodes (w-LEDs). The substitution of Sr with Ca results in a red shift of the emission peak from 654 nm to 687 nm, with the Ca²⁺substituted sample achieving an internal quantum efficiency (IQE) of 83.2%, surpassing that of SrLiAl₃N₄:0.02Eu²⁺ (SLAN:0.02Eu²⁺). Temperature-dependent photoluminescence (PL) spectra demonstrate the remarkable thermal stability of the phosphor, maintaining 109.91% of its original intensity at 425 K, which is critical for the applications of high-power LEDs. Furthermore, the development of a warm w-LEDs device yields a correlated color temperature (CCT) of 4044 K and a luminous efficacy of 99.2 lm/w, with a color rendering index (CRI) of 83.5, utilizing commercial YAG:Ce³⁺ yellow phosphor in conjunction with SCLAN:Eu²⁺. The performance characteristics of SCLAN:Eu²⁺ phosphors indicate significant potential as red color converters for high-power LEDs and backlighting displays.