Ca(Eu1-xLax)4Si3O13 Red Phosphor and its Application to Three-Band-Type White LEDs

To facilitate the application of three-band-type white LEDs, we developed a Ca(Eu1−xLax)4Si3O13 red phosphor that emits red light at a peak wavelength of 613 nm when it is excited by near-ultraviolet rays at a peak wavelength of 395 nm. The activator concentration dependence of the light conversion efficiency showed that the optimum composition of the red phosphor was at x=0.5 and that the conversion efficiency was 0.14. When a near-ultraviolet LED with an assumed external quantum efficiency of 0.40 was combined with Ca(Eu0.5La0.5)4 Si3O13 red phosphor and existing green and blue phosphors, the calculated luminous efficacy and general color rendering index of the resultant white LED were 21.6lm/W and 83.9, respectively.