Self-Activated Tungstate Phosphor for Near-Infrared Light-Emitting Diodes

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are promising for many applications in non-destructive testing, bio-imaging, and modern agriculture. However, developing self-activated NIR phosphors with high efficiency and excellent thermal stability is a great challenge for current research. In this work, a self-activated far-red to NIR emitting NaLaMgWO6 phosphor is prepared by the high-temperature solid-state reaction method, whose luminescence properties are investigated in detail. In addition, the introduction of Bi3+ ions as sensitizers enhances the emission intensity of far-red to NIR light (650-850 nm) through a Bi3+ -> WO66- energy transfer design strategy, resulting in an increased internal quantum efficiency (IQE) from 56.4% to 64.8% and thermal stability from 54% to 72% (420 K). Finally, the combination of NaLaMgWO6:Bi3+ with 365/460 nm commercial LED chip is prepared into NIR pc-LED devices, demonstrating satisfactory performance in the field of night vision detection and other wide range of practical applications.