Energy transfer enhanced broadband near-infrared phosphors: Cr3+/Ni2+ activated ZnGa2O4-Zn2SnO4 solid solutions for the second NIR window imaging

Near-infrared luminescent materials have attracted considerable interest because of their excellent performance in the field of optical imaging. Here, a series of Cr3+/Ni2+ co-doped near-infrared phosphors Zn1+ySnyGa2-2yO4 (ZSGO) were synthesized via a solid-state reaction. The phosphors show broad emissions in the range of 1100-1700 nm in the second NIR window. The emission intensity of Ni2+ could be greatly enhanced owing to the energy transfer from Cr3+ to Ni2+. The energy transfer mechanism was inferred from the excitation and emission spectra and the decay lifetime curve, which confirm that the primary process is the electric dipole-dipole interaction. In order to evaluate the potential optical imaging application, NIR-LED light source packages were fabricated with Cr3+/Ni2+ co-doped Zn1+ySnyGa2-2yO4 (ZSGO) phosphors and blue LED chips, which revealed high stability and a strong transilluminated biological tissue effect. These results indicate a great prospect in advanced optical imaging for NIR pc-LED applications.

Automated summary

A series of Cr3+/Ni2+ co-doped near-infrared phosphors Zn1+ySnyGa2-2yO4 (ZSGO) were synthesized, showing broad emissions in the second NIR window. The emission intensity of Ni2+ was greatly enhanced due to energy transfer from Cr3+ to Ni2+. The energy transfer mechanism was inferred from excitation and emission spectra and decay lifetime curve, indicating electric dipole-dipole interaction as the primary process. Additionally, NIR-LED light source packages fabricated with these phosphors and blue LED chips demonstrated high stability and significant transillumination effects on biological tissues, suggesting great potential for advanced optical imaging in NIR pc-LED applications.