Ce^(3+),Cr^(3+)co-doped garnet phosphors with yellow and near-infrared emission for white and near-IR dual-mode pc-LEDs

Cr^(3+)-activated phosphors with adjustable near-infrared(NIR)emission have attracted considerable attention due to their diverse applications across various fields.While modifying the emission wavelength of Cr^(3+)can be achieved by adjusting its coordination environment,the parity-forbidden d-d transition presents a challenge by limiting absorption and resulting in a low external quantum efficiency(EQE)in Cr^(3+)-doped phosphors.Moreover,longer emission wavelengths often coincide with reduced thermal stability.To address these issues,energy transfer from a sensitizer to Cr^(3+)has been proposed as a strategy to enhance both EQE and thermal stability of NIR emission.The selection of an appropriate host structure is crucial.In this study,a garnet structure,Ca_(2)LuMgScSi_(3)O_(12),was identified as a promising candidate for achieving efficient broadband NIR emission under blue light excitation.Specifically,Ca_(2)LuMgScSi_(3)O_(12):Ce^(3+)exhibited a yellow emission with exceptional internal quantum efficiency and EQE of up to 94.6%and 64.8%,respectively.By leveraging efficient energy transfer from Ce^(3+)to Cr^(3+),the Ca_(2)LuMgScSi_(3)-O_(12):Ce^(3+),Cr^(3+)phosphors exhibited tunable yellow to NIR emission.Notable,the highest EQE recorded for Ca_(2)LuMgScSi_(3)O_(12):Ce^(3+),Cr^(3+)was 56.9%,significantly surpassing that of the Cr^(3+)single-doped counterpart.Furthermore,the co-doped phosphor demonstrated thermal stability comparable to that of Ce^(3+)single-doped phosphor.Of particular significance,the developed prototype pc-LED emitted a combination of broadband white and NIR light,demonstrating potential applications in solar-like lighting,food analysis,and biomedical imaging.