Formation condition of red Ce3+ in Ca3Sc2Si3O12:Ce3+, N3- as a full-color-emitting light-emitting diode phosphor.

In this Letter, we study diffuse reflectance and photoluminescence spectra for O2− fully coordinated green-emitting Ce3+ and N3− partially coordinated red Ce3+ in Ca3Sc2Si3O12(CSS):Ce3+, N3− as a function of CeO2 and Si3N4 contents in the raw material. Our results indicate that the presence of N3− can enhance Ce3+ solubility in the form of red centers in CSS. At low Ce3+ concentration, green Ce3+ forms preferentially while red Ce3+ hardly forms even if N3− content in the raw material is sufficient. There exists a threshold concentration of green Ce3+; only beyond that can color tunable luminescence with enriched red emission be achieved. Energy transfer from green Ce3+ to red Ce3+ is also studied, as only the green Ce3+ is excited by blue light.