An intense green/yellow dual-chromatic calcium chlorosilicate phosphor Ca3SiO4Cl2:Eu2+-Mn2+ for yellow and white LED

A series of intense green/yellow phosphors Ca3SiO4Cl2:Eu2+,Mn2+ was synthesized by a high-temperature solid-state reaction. Their luminescent properties were characterized by means of powder diffuse reflection, photoluminescence excitation and emission spectra, and lifetime and temperature-dependent emission spectra in the temperature range of 10-450 K. The phosphors Ca3SiO4Cl2:Eu2+,Mn2+ show intense broad absorption bands between 250 and 450 nm, matching well with the near-ultraviolet (380-420 nm) emission band of InGaN-based chips, and exhibit two dominating bands situated at 512 and 570 nm, ascribed to the allowed 5d -> 4f transition of the Eu2+ ion and the T-4(1g)((4)G)->(6)A(1g)(S-6) transition of the Mn2+ ion, respectively. The lifetime of the Eu2+ ion decreases with increasing the concentration of the Mn2+ ion, strongly supporting an efficient energy transfer from Eu2+ to Mn2+. By combining with near-ultraviolet (similar to 395 nm) InGaN chips, intense yellow light-emitting diodes (LEDs) with a much lower ultraviolet light leakage were successfully fabricated based on the Ca3SiO4Cl2:Eu2+,Mn2+ phosphor, and intense white LEDs were made based on a blend of blue chlorophosphate phosphor and the green/yellow phosphor Ca3SiO4Cl2:Eu2+,Mn2+. The color coordinate, correlated color temperature T-c, general color-rendering index R-a, and luminous efficiency of the fabricated white LEDs are (0.3281, 0.3071), 6065 K, 84.5, and 11 lm/W, respectively. (C) 2008 The Electrochemical Society.