low scattering loss, exceptional penetrability, and characteristic interactions with organic functional groups. NIR light sources thereby have widespread applications in machine vision, communications, medical diagnostics, spectroscopy, etc. [1][2][3][4][5] In particular, NIR spectroscopy is a quick, convenient, and nondestructive analytical technique in the food industry and biomedical and environmental fields, [4] where continuous broadband NIR light sources are employed as key components. The combination of efficient blue light-emitting diode (LED) chips and NIR-emitting phosphors is emerging as an ideal strategy for building novel solid-state NIR light sources. Compared with current NIR sources (e.g., incandescent bulbs, halogen lamps, and LEDs), phosphor-converted LEDs (pc-LEDs) exhibit attractive advantages of compact size, low cost, tunable broadband emission, high efficiency, and excellent durability. Furthermore, miniaturized broadband NIR pc-LEDs can be easily integrated into smartphones or wearable devices enabling new functional applications. As the principal provider of spectral output, NIR phosphors are crucial to the popularization of NIR pc-LED light sources.Lanthanide ions (Pr 3+ , Tm 3+ , Sm 3+ and Eu 2+ ) as well as transition metal ions (Mn 2+ , Ni 2+ and Cr 3+ ) can generate the NIR luminescence when incorporated into appropriate host materials. [6][7][8][9][10][11] Among them, Cr 3+ is considered as an ideal NIR emitter due to its tunable broadband NIR emission and blue-light excitation features. Numerous Cr 3+ -activated NIR phosphors have been developed, such as garnets, [12][13][14][15][16] borates, [17][18][19][20] silicates, [21,22] gallogermanates, [23][24][25][26][27][28][29][30][31] phosphates, [32][33][34] fluorides, [35][36][37] etc. Some of them exhibit high internal quantum efficiency (IQE) and good thermal stability, such as GdAl 3 (BO 3 ) 4 :Cr 3+ (λ max = 740 nm, IQE = 91%, 98% intensity retention at 150 °C), [18] Gd 3 (Sc,Al) 2 Ga 3 O 12 :Cr 3+ (λ max = 760 nm, IQE = 98.6%, 92%@150 °C), [16] and Ca 3 Sc 2 Si 3 O 12 :Cr 3+ (λ max = 770 nm, IQE = 92.3%, 97.4%@150 °C). [15] However, their peak wavelengths are short (λ max < 800 nm) and considerable emissions are in the visible light region. Such spectral output would be insufficient for spectroscopic analysis because most molecular radicals have the characteristic absorption for NIR Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are newly emerging broadband NIR light sources. However, the lack of highperformance NIR-emitting materials limits their popularization. Herein, an anionic F-substitution strategy is presented to regulate the light absorption and emission of MgGa 2 O 4 :Cr 3+ phosphors. Accordingly, absorption enhancement as well as emission redshift and broadening are achieved for F-substituted MgGa 2 O 4 :Cr 3+ (MGOF:Cr 3+ ) phosphors, simultaneously with high efficiency and excellent thermal stability. Upon blue light excitation, the MGOF:0.02Cr 3+ phosphor exhibits a broadband NIR emission (65...
