A blue-light-excitable ultra-broadband near-infrared phosphor across the entire NIR-I and NIR-II windows

Abstract

Near-infrared (NIR) phosphor-converted light emitting diodes (pc-LEDs) are emerging as a highly promising NIR light source due to their compact design and high efficiency. However, their performance is constrained by the limited spectral range of available NIR phosphors. In this study, an ultra-broadband NIR phosphor La₃Al₂Ga₃SnO₁₄:Cr³⁺,Ni²⁺,Er³⁺ spanning the complete NIR-I and NIR-II spectral regions (700–1700 nm) has been successfully developed, demonstrating excellent compatibility with commercially available blue LED chips. The spectral properties and density functional theory calculations demonstrate that the Cr³⁺ ions occupy three distinct crystallographic sites within the LAGS:Cr³⁺ host lattice, corresponding to the [Al/Ga/SnO₆] octahedral coordination environments. The efficient energy transfer among these Cr³⁺ ions give rise to an exceptionally broad NIR emission band, characterized by a central wavelength of 910 nm and an extensive full width at half maximum of 341 nm. Gaussian deconvolution and fluorescence lifetime confirm the existence of efficient energy transfer pathways among these three crystallographic sites. Furthermore, the emission intensities at around 1200 and 1534 nm can be significantly enhanced through strategic codoping with Ni²⁺ and Er³⁺ ions, leading to a full NIR window coverage. A NIR pc-LED fabricated by employing the LAGS:0.05Cr³⁺,0.01Ni²⁺,0.01Er³⁺ and a blue LED chip exhibits exceptional performance in angiography, night vision, and nondestructive testing, demonstrating remarkable potential for diverse practical applications.