Defect-related luminescence behavior of a Mn4+ non-equivalently doped fluoroantimonate red phosphor

Constructing non-equivalent or non-octahedral substitution is a crucial strategy to gain Mn4+-doped fluoride red phosphors with short fluorescence lifetime, whereas their structural defect impact on photoluminescence (PL) property remains unrevealed. Here, a non-equivalently doped RbSbF6:Mn4+ (RSFM) with high quantum efficiency of 88 % and thermal stability of 121 % at 425 K is newly reported to probe the defect-related PL behavior. Formation energy calculation implies that an interstitial defect was formed to balance charge and stabilize crystal structure. Concentration-dependent decay studies reveal that Mn4+ emission is quenched mainly by energy transfer to neighbor defect . The large ionic radius of Sb5+ and defect leading to a premature optimal doping (0.11 mol%) is demonstrated by refined contrast of crystal structure and substitution mode among various Mn4+-doped prototypes. A couple of medium 4T2 state energy and energy difference between Mn4+ level with valence band maximum enables its superior thermal stability. Higher defect concentration slightly aggravates this thermal quenching. Using RSFM red phosphor in white light-emitting diode offers a wide-color-gamut of 121% NTSC for backlight display. This work would provide a new perspective to understand the defect effect on the PL behavior of Mn4+ special asymmetrically doped fluorides.