Efficient rare-earth free red-emitting Ca2YSbO6:Mn4+,M(M = Li+, Na+, K+, Mg2+) phosphors for white light-emitting diodes

Abstract

Owing to its low-cost and satisfactory luminescent-emission performance in warm white light-emitting diodes (w-LEDs), the non-rare-earth Mn⁴⁺-activated red phosphor has become a promising competitor of commercial rare-earth doped phosphor. In this study, a series of novel red-light emitting phosphors based on Ca₂YSbO₆:Mn⁴⁺ have been developed successfully by a conventional solid-state reaction. The structural and luminescent properties of these phosphors are systematically investigated. The as-prepared Ca₂YSbO₆:Mn⁴⁺ product exhibits a broad excitation band ranging from 250 to 600 nm and an abnormal intense deep-red emission centered at 680 nm with a full width at half maximum (FWHM) of ∼46 nm. The optimal Mn⁴⁺ doping concentration is about 0.3 mol%, and the concentration quenching mechanism is determined to be a dipole–dipole interaction. Impressively, the Ca₂YSbO₆:0.003Mn⁴⁺ phosphor shows an outstanding quantum efficiency of 62.6% and an excellent thermal stability. In addition, the effect of Li⁺, Mg²⁺, Na⁺ and K⁺ dopants on the luminescent properties of Mn⁴⁺-doped Ca₂YSbO₆ phosphors is elucidated. Furthermore, by employing the as-prepared Ca₂YSbO₆:Mn⁴⁺ as a red component, a warm w-LED with high color rendering index (R_a = 87.5) and low correlated color temperature (CCT = 3255 K) can be acquired. It is believed that the present phosphor has a potential application as a supplement of the red component for warm w-LEDs.