Color-tunableness of Er3+/Eu3+ co-doped BiOCl phosphors for near ultraviolet excitation

Abstract

In this paper, Er3+/Eu3+ co-doped BiOCl phosphors are synthesized by the conventional solid state method at 500℃, which are characterized by XRD, SEM, absorption spectra, excitation spectra and emission spectra. XRD analysis indicates that the samples exhibit pure tetragonal phase BiOCl. In SEM pictures, the samples exhibit smooth plate-like particles. The absorption spectra indicate that Er3+/Eu3+ ion dopants result in an impurity energy level, and the excitation spectra show that the sample has excellent broadband near ultraviolet (NUV)-exciting ability, which is due to the electronic transitions of the BiOCl bandgap. Under at 380 nm excitation, the emission bands located at 410 nm (2H9/2→4I15/2), 525 nm (2H11/2→4I15/2), 554 nm (4S3/2→4I15/2), 673 nm (4F9/2→4I15/2) of Er3+ ions, and 581 nm (5D0→7F0), 594 nm (5D0→7F1), 622 nm (5D0→7F2), 653 nm (5D0→7F3), 699 nm (5D0→7F4) of Eu3+ ions can be observed, respectively. Moreover, contrary to most of the Er3+/Eu3+-activated phosphors, the Er3+/Eu3+ co-doped BiOCl phosphor shows the unique and effective emission of the violet (Er3+) and far-red (Eu3+), which results from the particular structure of BiOCl crystals. The tunability in color of emitted radiation has been visualized by using chromaticity diagram on changing the doping concentration. Results show that the Er3+/Eu3+ co-doped BiOCl is a promising phosphor for near UV white LEDs.