Intense Green/Yellow Dual-Chromatic Calcium Chlorosilicate Phosphor Ca3SiO4Cl2:Eu2+–Mn2+ for Yellow and White LED, An
journal contributionposted on 17.03.2008, 00:00 by Weijia Ding, Jing Wang, Zongmiao Liu, Mei Zhang, Qiang Su, Jinke Tang
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 4T1g 4G → 6A1g 6S 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 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 Tc, general color-rendering index Ra, and luminous efficiency of the fabricated white LEDs are 0.3281, 0.3071, 6065 K, 84.5, and 11 lm/W, respectively.