Dual‐Function Al 3+ /B 3+ Introducing Strategy for Silica Phase Control and Enhanced Interstitial Deep‐Red Emission of Samarium (II)

ABSTRACT The exploration of highly efficient deep‐red luminescent materials is crucial for advancing white light‐emitting diodes (LEDs), indoor plant growth, and polycrystalline silicon solar cells. Here, we realize sharp deep‐red emission from interstitial Sm 2+ in silica through a dual‐function Al 3+ /B 3+ codoping strategy. The interstitial Sm 2+ exhibits a dominant emission centered at 683 nm with a broad excitation band ranging from 250 to 550 nm. The co‐introduction of Al 3+ and B 3+ facilitates the phase transition from α ‐quartz to α ‐cristobalite, which is more favorable for samarium accommodation, as revealed by density functional theory (DFT) calculations. Meanwhile, the co‐introducing of Al 3+ and B 3+ increases the amount of Sm 2+ as proved by the UV‐Vis‐NIR diffuse reflectance and X‐ray absorption near‐edge structure (XANES) spectra. These two factors synergistically enhance the emission intensity of Sm 2+ compared with that in the Al 3+ and B 3+ singly doped samples. Specifically, Al 3+ , B 3+ and Sm 2+ doped α ‐cristobalite (SiO 2 :Al 3+ ,B 3+ ,Sm 2+ ) presents heat resistance up to 600°C and great water resistance abilities as proved thermally treated in air and hot‐water immersion assessments. This work demonstrates a strategy to realize and enhance the Sm 2+ emission by interstitial occupation and microenvironment adjustment.