Structural and optical properties of Dy3+:YAlO3 phosphors for yellow light-emitting diode applications

Abstract

The spectroscopic properties of a series of Dy3+ single-doped and Dy3+/Nd3+, Dy3+/Tb3+, and Dy3+/Tm3+ co-doped YAlO3 (yttrium aluminum perovskite, YAP) phosphors were investigated and compared through the measurements of optical absorption, emission spectra, and fluorescence decay curves. For the Dy3+ ion single-doped samples, the intensity of each absorption band increases with an increment in Dy3+ ion doping concentration, and the identified strong absorption peak at 447 nm indicates that Dy3+:YAP phosphors are suitable to be pumped by a blue laser diode (LD). For all co-doped samples, absorption peaks of Dy3+ ion along with some of the absorption bands of Nd3+, Tb3+, and Tm3+ ions are observed. Under 351 and 447 nm excitation, a prominent emission peak at 572 nm was obtained in all the samples, corresponding to Dy3+: 4F9/2 → 6H13/2 transition. Here, 2 at% Dy3+:YAP phosphor exhibits the highest yellow emission intensity under 447 nm pumping. Among the three kinds of Dy3+ co-doped phosphors, Dy3+/Tb3+:YAP phosphor possesses the dominant yellow emission. The fluorescence decay curves show exponential behaviour and are fitted well. The Commission International de L'Eclairage (CIE) chromaticity coordinates were calculated following the respective emission spectra, and it is found that all the coordinates locate in the yellow region. The energy transfer (ET) processes were investigated and the concentration quenching mechanism was discussed. The obtained results suggest that Dy3+-activated YAP phosphors are good candidates for yellow LED applications.