Aliovalent Substitution Toward Reinforced Structural Rigidity in Ce3+-Doped Garnet Phosphors Featuring Improved Performance
Highly efficient phosphors with thermal stable and color-tunable emission are urgent for the fabrication of phosphor-converted white light-emitting diodes (pc-WLEDs). Currently developed many engineering strategies are generally successful in photoluminescence tuning, unfortunately, along with severely deteriorated emission intensity/efficiency and/or thermal stability. Herein, an efficient aliovalent substitution strategy toward reinforced structural rigidity is proposed and experimentally demonstrated. By incorporating Be2+ ion into Lu2SrAl4SiO12:Ce3+ phosphor, the phosphor shows an enhanced internal/external quantum efficiency from 79.2%/26.7% to 84.5%/32.9%, facilely tuned emission color from green (peaking at ~512 nm) to yellow (peaking at ~552 nm), and zero thermal quenching even up to 200 °C. The Be2+ substitution at Al2/Si2 site enables stable and rigid local surroundings around Ce3+ activator, responsible for the unprecedented performances. Besides, high-quality warm WLED device with luminous efficiency of 158.1 lm/W, correlated color temperature of 3858 K and high color render index of 81.7, are obtained by combining Lu2SrAl4SiO12: Ce3+, Be2+ as yellow emitter, CaAlSiN3: Eu2+ as red emitter and blue-emitting InGaN chip. The finding highlights a new strategy for performance optimization of LED phosphor by selecting rigid covalent compounds with further reinforced structural rigidity via aliovalent substitution.