Abnormal Bi3+ activated NIR phosphor toward multifunctional LED applications

https://doi.org/10.1016/j.ceramint.2023.09.322

Herein, the strategy of replacing Ge⁴⁺ with smaller Si⁴⁺ was adopted to realize the site-selective occupation of Bi³⁺ activator in the small ring and obtain a near-infrared light-emitting in Zn₂(Ge,Si)O₄. 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 Bi³⁺-activated NIR-emitting phosphors, but also provides thoughts for revealing the potential NIR luminous mechanism of Bi³⁺.