Near ultraviolet light excitable highly efficient blue-green multicolour warwickite phosphor, ScCaO(BO3):Ce3+, Tb3+

Abstract

Ce³⁺, Tb³⁺ co-doped multicolour emission phosphors show highly efficient green emission by energy transfer from Ce³⁺ to Tb³⁺. However, an emission peak of near ultraviolet (UV) LEDs, which is around 390 nm, does not match the absorption wavelengths in most Ce³⁺, Tb³⁺ co-activated phosphors. This spectral mismatch causes low emission efficiencies in phosphor-converted white LEDs (pc - wLEDs). In this study, Ce³⁺, Tb³⁺ co-activated ScCaO(BO₃) (SCBO) multicolour phosphors with the orthorhombic warwickite structure were successfully obtained by the conventional solid-state reaction method for the first time. The phosphors exhibit bright blue or green emission under near UV excitation around 390 nm due to energy transfer from Ce³⁺ to Tb³⁺. In SCBO, Ce³⁺ and Tb³⁺ ions were substituted on two respective order sites, CaO₆ and ScO₆, leading to high emission efficiency. The internal quantum efficiency of SCBO : 0.01Ce³⁺, 0.15Tb³⁺ was reported to be 62% under the near UV excitation at 390 nm. In order to verify the potential of optical devices, particularly backlighting LEDs, the Rietveld refinement, photoluminescence properties, and decay curve analysis using the Inokuti–Hirayama model are described in this study.