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

Abstract 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⁺ → WO₆^6– 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.