Ultra-transparent β-Ga ₂O ₃:Cr ³⁺ glass-ceramics enabling high-efficiency true-transmission near-infrared light-emitting diodes

Near-infrared phosphor converted light-emitting diodes (NIR pc-LEDs), one of the most promising NIR light sources, have garnered significant attention owing to their compact structure, long lifetime and energy conservation. Despite these advantages, commercial NIR pc-LEDs employing pseudo-transmission configurations -where NIR phosphor and silicone composites are directly coated on blue LED chips-suffer from critical limitations in thermal management that severely deteriorates their NIR output performance. To address these intrinsic limitations, we developed an oxygen-coordination-competitive crystallization strategy to engineer high-transparency β-Ga₂O₃:Cr³⁺ glass-ceramics (GC). This strategy leveraged the strong oxygen affinity of Ga³⁺ ions, which during thermal processing drove the directional migration and recombination of Ga³⁺ and O^2- ions within the isolated [GaO4] tetrahedral network. This controlled phase evolution enabled localized crystallization of β-Ga₂O₃:Cr³⁺nanocrystals while maintaining high-transparency. The optimized β-Ga₂O₃:Cr³⁺GC ( 0.4 mm thickness) achieved remarkable 81.2% NIR transmittance, approaches internal quantum efficiency (IQE≈100%) and high thermal stability (89%@423 K). When employing this high-transparency β-Ga₂O₃:Cr³⁺ GC as NIR conversion material, NIR GC converted LEDs (GCc-LEDs)  achieved 568 mW NIR output power at 500 mA drive current with a photoelectric conversion efficiency of 13%.  The demonstrated performance metrics of  NIR GCc-LEDs positioned this technology as an ideal NIR illumination source for next-generation point-of-care diagnostics, intelligent night vision systems, and non-destructive testing applications.