A novel Dy3+-activated single-phase white light-emitting phosphor for solid-state lighting

Abstract

The radius of trivalent scandium ions is much smaller than those of other rare earth ions and thus research studies targeting the substitution of the scandium site with other light-emitting rare earth ions are rarely reported. In our present work, special attention is paid to the effect of Dy³⁺ doping on the crystal structure, atomic site occupancy and luminescence properties of the ScCaBO₄ host as Dy³⁺ often serves as an individual activator for single-phase white light-emitting phosphors. Herein a series of ScCaBO₄:Dy³⁺ phosphors were prepared by solid-state reactions. The phase composition was recorded by X-ray diffraction analysis and XRD refinement reveals that a pure phase could be maintained even when the Dy³⁺ concentration reaches 11%. Scanning electron microscopy (SEM) was utilized to observe the morphology and EDS mapping was used to investigate elemental distribution. The luminescence performances of the phosphors were investigated using UV-vis diffuse reflectance spectra, steady-state excitation and emission spectra and also transient luminescence decays. Dy³⁺ luminescence can be ascribed to its ⁴F_9/2 → ⁶H_15/2, ⁶H_13/2 and ⁶H_11/2 transitions, producing blue, yellow and red emissions. The Dy³⁺ concentration was further optimized at 3%, at which the CIE coordinates and fluorescence lifetimes were (0.425, 0.413) and 0.546 ms, respectively. Thermal quenching studies of the ScCaBO₄:0.03Dy³⁺ phosphor show that Dy³⁺ luminescence at 400 K can maintain 60.91% of its initial value measured at room temperature. All the results indicate that the ScCaBO₄:Dy³⁺ inorganic phosphors could be a promising single component phosphor for near-UV chip based WLEDs.