Enhanced luminescence of novel Ca3B2O6:Dy3+ phosphors by Li+-codoping for LED applications

The Ca3−xB2O6:xDy3+ (0.0 ≤ x ≤ 0.105) and Ca2.95−yDy0.05B2O6:yLi+ (0 ≤ y ≤ 0.34) phosphors were synthesized at 1100 °C in air by solid-state reaction route. The as-synthesized phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation (PLE) and photoluminescence (PL) spectra. The PLE spectra show the excitation peaks from 300 to 400 nm is due to the 4f–4f transitions of Dy3+. This mercury-free excitation is useful for solid state lighting and light-emitting diodes (LEDs). The emission of Dy3+ ions upon 350 nm excitation is observed at 480 nm (blue) due to the 4F9/2 → 6H15/2 transitions, 575 nm (yellow) due to 4F9/2 → 6H13/2 transitions and a weak 660 nm (red) due to 4F9/2 → 6H11/2 emissions, respectively. The optimal PL intensity of the Ca3−xB2O6:xDy3+ phosphors is found to be x = 0.05. Moreover, the PL results from Ca2.95−yDy0.05B2O6:yLi+ phosphors show that Dy3+ emissions can be enhanced with the increasing codopant Li+ content till y = 0.22. By simulation of white light, the CIE of the investigated phosphors can be tuned by varying the content of Li+ ions, and the optimal CIE value (0.300, 0.298) is realized when the content of Li+ ions is y = 0.22. All the results imply that the Ca2.95−yDy0.05B2O6:yLi+ phosphors could be potentially used as white LEDs.