Abnormal Bi3+ activated NIR phosphor toward multifunctional LED applications

Herein, the strategy of replacing Ge 4+ with smaller Si 4+ was adopted to realize the site-selective occupation of Bi 3+ activator in the small ring and obtain a near-infrared light-emitting in Zn 2 (Ge,Si)O 4 . The designed phosphor exhibits a broad NIR emission with FWHM ≈104 nm in the 650−860 nm region, with a center emission wavelength of about 750 nm. Interestingly, the more sensitive four-member ring sites gradually replaced the six-member ring sites and realized a large-scope photoluminescence regulation from blue to NIR by just after the crystal field engineering. The possible reasons for this phenomenon can be interpreted by centroid shift ( ε c ) and crystal field splitting ( ε cfs ). This work not only provides new insights for the development of Bi 3+ -activated NIR-emitting phosphors, but also provides thoughts for revealing the potential NIR luminous mechanism of Bi 3+ .