Enhancement of the photoluminescence properties of Ba1.98SiO4−δN2/3δ:Eu0.02 phosphors and their application to green LEDs

Abstract

A green emitting Ba1.98SiO4−δN2/3δ:Eu0.02 phosphor with an appreciable intensity was synthesized using the gas-reduction–nitridation (GRN) method. SEM revealed agglomerated Ba1.98SiO4−δN2/3δ:Eu0.02 particles with irregular morphologies and a primary particle size of 1–2.5 μm. The phosphor showed emission lines of Eu2+ corresponding to the 4f65d1 → 4f7 transition under 370 nm excitation. As the GRN process was conducted to incorporate N3− into the lattice, both the excitation and emission intensity of Ba1.98SiO4−δN2/3δ:Eu0.02 were enhanced greatly compared to Ba1.98SiO4:Eu0.02. The decay time of Ba1.98SiO4−δN2/3δ:Eu0.02 showed that N entered the Ba1.98SiO4:Eu0.02 lattices to replace O to form a NO point defect. The electroluminescence intensity of Ba1.98SiO4−δN2/3δ:Eu0.02 at 503 nm increased with increasing forward bias current. Intense green LEDs were fabricated by coating the synthesized phosphors on the cap of the near-ultraviolet InGaN LEDs (λem = 375 nm). Overall, this phosphor appears to be a promising candidate for solid-state lighting applications.