Achieving ultra-broadband NIR Gd2Mg3Ge3O12:Cr3+,Yb3+garnet phosphors through energy transfer

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) light sources have great potential for applications in information encryption, night vision, and non-destructive testing. However, designing efficient NIR phosphors with wide emission band remains a significant challenge. Here, we report a garnet-type NIR phosphor Gd2Mg3Ge3O12:Cr3+,Yb3+ (GMG:Cr3+,Yb3+). The GMG:0.06Cr3+ phosphor shows a broadband emission peaking at 828 nm under 450 nm excitation, with a full width at half maximum (FWHM) of 188 nm. When Yb3+ ions are introduced to construct Cr3+-Yb3+ energy transfer, the obtained GMG:Cr3+,Yb3+ phosphor displays further widened emission band with a FWHM of 272 nm. Moreover, GMG:Cr3+,Yb3+ phosphor and commercial blue LED chips are combined to create NIR pc-LEDs, which have a photoelectric efficiency of 5.76% @ 100 mA and a maximum NIR output power of 17.21 mW @ 100 mA, demonstrating its potential applications in night vision, non-destructive testing, and information encryption.