KSr4(BO3)3:Pr3+: A new red-emitting phosphor for blue-pumped white light-emitting diodes

A novel red phosphor KSr4(BO3)(3): Pr+ was prepared by using a solid-state reaction method, and its photoluminescence and charge compensator effect (Li+) were investigated. The synthesized phosphors were characterized by X-ray diffraction (XRD), scanned electron microscope (SEM) and photoluminescence (PL) spectroscopy. The as-prepared material indicates that Pr+ ions occupy Sr+ sites in the lattice of KSr4(BO3)(3) with micron-scale irregular morphology. Their excitation bands at 449, 475 and 487 nm are originated from the transitions of H-4 -> P-2, H4 -> P-1 and H-4 -> P-0 of Pr+ ion. Under 449 nm excitation, the emission of Pr+ at 587, 606 and 627 nm are attributed to D-2 -> H-5, P-0 -> H-6 and P-0 -> F-2. The optimized doping concentration of Pr+ in KSr4-x(BO3)(3): xPr(+) is determined to be x = 0.015. By codoping Li+ in KSr4(BO3)(3): Pr+ to compensate the charge unbalance, the intensities of emission spectra at 606 nm can be increased greatly. The nonradiative concentration quenching among two nearest Pr+ ions occurs via dipole-dipole interaction based on the Dexter theory. The Commission Internationale de lEclairage (CIE) chromaticity coordinates are (0.645, 0.354) for KSr4(BO3)(3): Pr+ Li+ and (0.644, 0.355) for KSr4(BO3)(3): Pr+ Li+ respectively. The decay curves of the selected samples are also studied in detail. The result shows that KSr4(BO3)(3): Pr+ is promising candidate for red phosphors in the fabrication of white light-emitting diodes via blue LED chips. (C) 2017 Elsevier B.V. All rights reserved.