摘要
Ultra-broadband near-infrared (NIR) lighting sources covering NIR Ⅰ to III regions are pivotal components for NIR spectroscopy devices. However, achieving ultra-broadband and efficient emission covering the entire NIR Ⅰ to III regions remains a significant challenge. To address this, we selected Mg 7 Ga 2 GeO 12 as host material to realize ultra-broadband NIR emission. Density functional theory calculations on formation energies confirmed the feasibility of doping both Ni 2+ and Cr 3+ within Mg 7 Ga 2 GeO 12 . Band structure calculations reveal a significantly reduced band gap upon the doping of Ni 2+ . Following that, we synthesized Mg 7 Ga 2 GeO 12 :Ni 2+ through conventional solid-state-reaction method. This phosphor exhibits broadband NIR emission with a full-width-at-half-maximum of 377 nm in the range of NIR II ∼ III (1100–2100 nm). To further enhance the emission efficiency, we co-doped Mg 7 Ga 2 GeO 12 :Ni 2+ phosphor with Cr 3+ . This co-doping strategy not only dramatically enhances the Ni 2+ emission intensity, but also extends the lower limit of emission band to 600 nm. However, a spectral gap around 1150 nm remains between Cr 3+ and Ni 2+ emission centers. To bridge this spectral gap, we employed LiScSiO 4 :Cr 3+ phosphor alongside Mg 7 Ga 2 GeO 12 :Ni 2+ ,Cr 3+ phosphor to fabricate a phosphor converted LED (pc-LED) with ultra-broadband NIR emission covering entire NIR Ⅰ to III regions. By utilizing this pc-LED as the lighting source for NIR spectral detection, multiple organic functional group signals can be identified simultaneously in NIR II and III bands from 1000 to 2100 nm. The performance of such an NIR pc-LED not only confirms the application potential of Mg 7 Ga 2 GeO 12 :Ni 2+ ,Cr 3+ phosphor in non-destructive spectral analysis but also underscores the feasibility of combining two phosphors to achieve ultra-broadband NIR pc-LEDs, rendering them suitable to be lighting sources for portable spectrometers.
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