Optical properties of Ba2SiO4:Eu2+ phosphor for green light-emitting diode (LED)

Eu2+ activated Ba2SiO4 phosphors were synthesized at 1573 K by solid-state reactions under a weak reductive atmosphere and systematically investigated by photoluminescence excitation and emission spectra, diffuse reflectance spectra, concentration quenching process and lifetime. The intensive green LEDs were fabricated by combining the synthesized phosphors with near-ultraviolet InGaN chips (lambda(em) = 395 nm). The Commission Internationale de I'Eclairage color coordinate of the fabricated LEDs is calculated to be x = 0.1904, y = 0.4751 under 20 mA forward-bias current. The dependence of the green LEDs on forward-bias currents shows that as the current increases, the relative intensity simultaneously increases and the color coordinate presents excellent stability, falling in the standard area of the Institute of Transportation Engineers for traffic lights and the Society of Automotive Engineers for automotive displays. These results indicate that the fabricated phosphor-converted green LEDs show great potential for traffic lights and automotive display applications. (C) 2006 Elsevier Ltd. All rights reserved.