High-Efficiency Continuous-Luminescence-Controllable Performance and Antithermal Quenching in Bi3+-Activated Phosphors.

ABSTRACT

Recently, Bi3+-activated phosphors have been widely researched for phosphor-converted light-emitting diode (pc-LED) applications. Herein, novel full-spectrum A3BO7Bi3+ (A = Gd, La; B = Sb, Nb) phosphors with a luminescence-tunable performance were achieved by a chemical substitution strategy. In the La3SbO7 host material, a new luminescent center was introduced, with Gd3+ replacing La3+. The photoluminescence (PL) spectra show a large blue shift from 520 to 445 nm, thus achieving regulation from green to blue lights. Moreover, a series of solid solution-phase phosphors La3Sb1-xNbxO7Bi3+ were prepared by replacing Sb with Nb, and a PL spectral tunability from green (520 nm) to orange-red (592 nm) was realized. Temperature-dependent PL spectra show that La3-xGdxSbO7Bi3+ phosphors have excellent thermal stability. Upon 350 nm excitation, the PL intensity of La3-xGdxSbO7Bi3+ phosphors at 150 °C remained at more than 93% at room temperature. With Gd3+ doping, the thermal stability gradually improved, and LaGd2SbO70.03Bi3+ represents splendid antithermal quenching (135.2% at 150 °C). Finally, a full-visible spectrum for pc-LED with a high color-rendering index (Ra = 94.4) was obtained. These results indicated that chemical substitution is an effective strategy to adjust the PL of Bi3+, which is of great significance in white-light illumination and accurate plant lighting.