An efficient and stable green phosphor SrBaSiO4:Eu2+ for light-emitting diodes

Abstract

Eu 2+ -activated strontium–barium silicate, SrBaSiO 4 :Eu 2+ , which is an intermediate phase between Sr 2 SiO 4 and Ba 2 SiO 4 , was synthesized by a solid-state reaction. The synthesized phosphor was efficiently excited by a broad spectral range of near UV between 300 and 450 nm, and exhibited a strong and wide green emission. As the doped Eu 2+ concentration increased from 0.005 to 0.18 (molar ratio), the emission wavelength shifted from 509 to 521 nm, and this red-shift phenomenon was discussed through a band-gap model. The concentration quenching mechanism was calculated to be a dipole–quadrupole interaction. It showed good thermal stability with T 1/2 of 170 °C and high internal quantum efficiency (78%). A green LED was fabricated with SrBaSiO 4 :Eu 2+ and a 395 nm-emitting InGaN chip and it showed a superior current tolerant property. All the results indicate that this phosphor is a good candidate as green component in fabrication of phosphor-converted white LEDs.