Enhanced Luminescence of Long-Wavelength Broadband Near-Infrared Germanate Phosphors

Long-wavelength broadband near-infrared (NIR) phosphors have attracted considerable interest in the fields of medical cosmetology and organic detection because of their special emission band. Herein, Ca2GeO4(CGO): Cr4+ NIR phosphor, presenting a broadband emission with longer wavelength ranging from 1100 to 1600 nm, has been synthesized. Further, the luminescence intensity and quantum efficiency of Cr4+ could be obviously improved via the energy transfer from Eu3+ to Cr4+. The energy transfer is dominated by the dipole–dipole mechanism, which can be inferred from the spectra and the decay curves. Furthermore, in order to evaluate the potential application, an NIR phosphor-converted light-emitting diode (pc-LED) based on blue chip has been prepared. Consequently, CGO: Eu3+, Cr4+ exhibits proper output power and wider half-width than the NIR LED chip, indicating its great prospect for long-wavelength NIR pc-LED applications.