ZnGa 2 O 4 :Cr 3+ /Ni 2+ Transparent Glass‐Ceramics for High‐Performance Monolithic GCc‐LED Sources With Broadband NIR‐I/II Emission

The growth of artificial intelligence, Internet of Things, and wearable health monitoring demands miniaturized, high‐efficiency near‐infrared‐II (NIR‐II) light sources. However, conventional NIR‐II phosphor‐converted light‐emitting diodes (pc‐LEDs) suffer from organic reabsorption, poor 400 nm‐light penetration, and low stability. Here, we propose a transparent glass‐ceramic‐converted LED (GCc‐LED) platform for NIR‐II light sources. ZnGa 2 O 4 :Cr 3+ /Ni 2+ glass‐ceramics (GCs) were designed via phase diagram analysis and molecular dynamics simulations. Notably, Cr 3+ /Ni 2+ ions act as both luminescent centers and microstructure regulators, increasing the transparency of the GCs from ∼6.79% to ∼85.03% (@690 nm). Under 400 nm excitation, efficient Cr 3+ →Ni 2+ energy transfer enables ultra‐broadband dual‐band NIR‐I/II emissions, with internal and external quantum efficiencies of 78.80% and 27.58%, respectively. We assembled GC converters with LED chips to make a GCc‐LED device, achieving a NIR output power of 34.05 mW and a 400 nm‐to‐NIR conversion efficiency of 2.87% (at 500 mA). Importantly, the GCc‐LED avoids NIR‐II reabsorption and exhibits stable spectra. They also exhibit strong potential in non‐destructive molecular sensing, high‐resolution night vision, and transmissive bioimaging. This work establishes transparent GCs as a viable platform for compact NIR‐II light sources, enabling portable spectroscopy and smart sensing.