Broadband emission of single-phase Ca3Sc2Si3O12:Cr3+/Ln3+ (Ln = Nd, Yb, Ce) phosphors for novel solid-state light sources with visible to near-infrared light output

Novel single-component phosphors Ca3Sc2Si3O12:Cr3+/Ln(3+) (CSS:Cr-3(+)/Ln(3)(+), Ln = Nd, Yb, Ce) with broadband near-infrared (NIR) emissions are synthesized. Their phase structure, photoluminescence properties and energy transfer between Cr3+ and Ln(3+) ions are investigated. In the CSS host, Cr3+ ions occupy Sc3+ sites with low-field octahedral coordination, and thus show a broadband emission in 700-900 nm under the blue light excitation. Nd3+, Yb3+ and Ce3+ ions substitute Ca2+ sites in CSS, where Nd3+ and Yb3+ ions emit the NIR light in 900-1100 nm and their excitation efficiencies at similar to 450 nm are greatly enhanced by utilizing the energy transfer from Cr3+ to Nd3+/Yb3+ ions. Ce3+ ions can further enhance the absorption of CSS:Cr3+/Ln(3+) phosphors to the blue light, and at the same time contribute to the visible emission in 480-650 nm. Furthermore, CSS:Cr3+/Ln(3+) phosphors show good thermal stability, and approximately 79% of the initial emission intensity is sustained at 150 degrees C. A phosphor-converted LED (pc-LED) prototype is fabricated by integrating the as-prepared phosphor CSS:Cr3+/Ln(3+) and the commercial phosphor CaAlSiN3:Eu2+ with the blue LED chip, showing a super broadband emission ranging from 450 to 1100 nm. This finding shows the potential application of CSS:Cr3+/Ln(3+) phosphors in broadband NIR pc-LEDs or super broadband LED sources with visible to NIR light output.