摘要
Most of the NIR emitting materials reported until now are limited by their low external quantum efficiency.Developing highly efficient and tunable broadband near-infrared phosphors remains a significant challenge for realizing their multi-applications.Herein,a gallate,LiGaGe_(2)O_(6),was selected as the host for Cr^(3+)doping,while its crystal and electronic structures were revealed using the Rietveld refinement and DFT calculations.On irradiating this LiGaGe_(2)O_(6):Cr^(3+)phosphor with 460 nm blue light,it generates a broadband NIR emission(λ_(em)=830 nm)covering the 700-1200 nm region with a full width at half maximum of 192 nm.A promising external quantum efficiency(EQE)of 27.9%could be achieved at an optimal Cr^(3+)content of 0.06.It was found that a spectral tuning with the peak position in the range of 830-890 nm was realized by the Sc^(3+)-Ga^(3+)substitution with a decreasing crystal field strength.Meanwhile,the optimized Li(Ga_(0.24)Sc_(0.70))Ge_(2)O_(6):Cr^(3+)exhibited an enhanced EQE of 47.8%.The variation of emission thermal stability by Sc^(3+)substitution was investigated.The prepared phosphor-converted light-emitting diode(pc-LED)device generated an intense NIR emission(25.3 mW at 100 mA)with a photoelectric efficiency of 10%.Thus,this work not only provides a novel high-performance broadband NIR phosphor for NIR pc-LED,but also demonstrates that cationic substitution is an effective strategy to tune and enhance the NIR optical properties of Cr^(3+)-doped phosphors.
基金
funded by the Science Foundation of Guangxi Province(no.2022GXNSFDA080005 and no.2022GXNSFBA035516)
the Guangzhou Scientific planning program(no.201804010260)
the National Natural Science Foundation of China(no.21601081).
