Enhanced luminescence and afterglow by heat-treatment in reducing atmosphere to synthesize the Gd3Al2Ga3O12: Ce3+ persistent phosphor for AC-LEDs

Yellow-emitting persistent phosphor Gd3Al2Ga3O12:Ce3+ (GAGG:Ce3+) was synthesized by two-step solid-state reactions. The phase evolution, luminescence, persistent luminescence, and thermal stabilities of GAGG:Ce3+ sintered in an O-2 atmosphere and annealed in a CO reducing atmosphere at different temperatures were investigated. Comparing with the samples sintered only in O-2, the samples annealed in CO show higher luminescence and afterglow and better thermal stability. Under 445 nm excitation, the luminescence and afterglow of GAGG:Ce3+ are similar with each other, displaying a broad yellow emission with a peak around 545 nm. By optimizing the sintering process, the internal quantum efficiency can reach as high as 71.3%. The time tau(80) is about 15 ms, which is much longer than 0.4 ms required for alternating current (AC)-LEDs. These results indicate the promising application of the GAGG:Ce3+ persistent phosphor for reducing flicker from AC-LEDs. (C) 2017 Elsevier B.V. All rights reserved.