Structure and luminescence of Gd3Ga3MgSiO12:Cr3+ garnet phosphor with highly efficient broadband near-infrared emitting toward pc-LED application
Doping Gd 3 Ga 3 Al 2 O 12 :Cr 3+ with Mg 2+ /Si 4+ pair to develop Gd 3 Ga 3 – y Al 2 – 2 x Mg x Si x O 12 : y Cr 3+ ( x = 0–1.0; y = 0.005–0.05) new garnet solid solution was implemented for the regulation of structure and photoluminescence. Rietveld refinement, SEM/TEM, and UV-Vis-NIR/photoluminescence spectroscopy analysis clarified that Mg 2+ /Si 4+ incorporation increasing resulted in the enlargement of the unit cell, the expansion/larger distortion of [(Ga,Al,Mg,Cr)O 6 ] octahedron, the decrease of crystal field strength, red-shifting and broadening of emission band, and shortening decay times. The optimal Gd 3 Ga 2.97 MgSiO 12 :0.03Cr 3+ phosphor realized broadband NIR emission (centered at ∼760 nm, full-width at half-maximum ∼114 nm) under 450 nm light excitation and exhibited high quantum efficiency (IQE=71.0 %, EQE=29.4 %) and good thermal stability (78.5 %@423 K). The NIR pc-LED fabricated by combining this optimal phosphor with a 450 nm blue LED chip showed satisfactory output power (∼26.83 mW) and conversion efficiency (10.02 %) under a driving current of 100 mA, indicating that this phosphor has huge potential utilized in the construction of NIR pc-LED applied in night vision and noninvasive medical diagnosis.
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