Enhancement of red emission in KLa(MoO4)(2):Eu3+, Bi3+ phosphor for WLEDs

摘要

A series of Bi3+ -Eu3+ co-doped KLa(MoO4)(2) phosphors were synthesized by a hydrothermal method. The obtained samples were characterized by power X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet visible absorption spectrometer and photoluminescence (PL) techniques. The products were pure monoclinic phase and were composed of octahedral particles. The PLE and PL spectra demonstrated that the phosphors could be excited by 395 nm and 465 nm, which were in good agreement with the emission wavelengths of the near-ultraviolet (near-UV) and blue LED chips, respectively, and emitted red light at about 618 nm owing to D-5(0) -> F-7(2) transition of Eu3+. It was found that the intensity of the red light was significantly enhanced by adding Bi3+, which was attributed to the sensitization of Eu3+ by Bi3+. The exchange interaction was the major energy transfer mechanism in KLa(MoO4)(2):Eu3+, Bi3+. Besides, the lifetime and chromaticity coordinates of single-doped Eu3+ and Eu3+ Bi3+ co-doped products were compared, respectively. All the results suggest that KLa(MoO4)(2): Eu3+, Bi3+ is a promising phosphor for white LEDs. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.