Dual-Shelled RbLi(Li₃ SiO₄ )₂ :Eu²⁺ @Al₂ O₃ @ODTMS Phosphor as a Stable Green Emitter for High-Power LED Backlights

The stability of luminescent materials is a key factor for the practical application in white light-emitting diodes (LEDs). Poor chemical stability of narrow-band green-emitting RbLi(Li₃ SiO₄ )₂ :Eu²⁺ (RLSO:Eu²⁺ ) phosphor hinders their further commercialization even if they have excellent stability against thermal quenching. Herein, we propose an efficient protection scheme by combining the surface coating of amorphous Al₂ O₃ and hydrophobic modification by octadecyltrimethoxysilane (ODTMS) to construct the moisture-resistant dual-shelled RLSO:Eu²⁺ @Al₂ O₃ @ODTMS composite. The growth mechanisms of both the Al₂ O₃ inorganic layer and the silane organic layer on the phosphor surface are investigated. The results remarkably improve the water-stability of this narrow-band green emitter. The evaluation of the white LED by employing this composite as the green component demonstrates that RLSO:Eu²⁺ @Al₂ O₃ @ODTMS is a promising candidate for the high-performance display backlights, and this dual-shelled strategy provides an alternative method to improve the moisture-resistant property of humidity-sensitive phosphors.