780nm长波长和196nm宽发射带石榴石近红外荧光粉Na2Lu2Ga4GeO12∶Cr3+OA

The development of compact light sources is urgently required for portable near-infrared(NIR)spec-trometers.In this context,phosphor-converted light-emitting diodes(pc-LEDs)show great promise.Among various candidates,Cr3+-activated NIR phosphors are considered highly competitive due to their high efficiency and tunable emission.However,most reported Cr3+-activated NIR phosphors suffer from a narrow full width at half maximum(FWHM<150 nm)and a short emission wavelength(λem<750 nm).In this work,a novel garnet-type NIR phosphor,Na2Lu2Ga4GeO12∶Cr3+(NLGG∶Cr3+),was designed and synthesized via a[Na+-Ge4+]co-substitution strategy.Under 468 nm blue light excitation,the optimized NLGG∶0.08Cr3+sample exhibits a broadband emission covering 600-1 100 nm with a peak at 780 nm and a FWHM of 196 nm,achieving an internal quantum efficiency(IQE)of 56%and an external quantum efficiency(EQE)of 22%.Spectral analysis and crystal field calculations confirm that the broadband emission originates from Cr3+ions occupying a single type of Ga3+site with an intermediate crystal field strength.The emission peak can be continuously tuned from 742 nm to 790 nm,accompanied by a broadening of the FWHM from 182 nm to 196 nm,by varying the Cr3+doping concentration.Finally,an NIR pc-LED device fabricated with this phosphor and a blue LED chip demonstrates its potential applications in biomedical imaging,night vision,and non-destructive testing.