Regulating Eu2+ Multisite Occupation through Structural Disorder toward Broadband Near-Infrared Emission

To promote the development of near-infrared (NIR) light sources in optoelectronic and biomedical applications, the discovery of NIR-emitting phosphor materials and their design principles are essential. Herein, we report a novel Eu2+-activated broadband NIR-emitting phosphor, BaSrGa4O8:Eu2+, which features multisite occupation due to Ba/Sr and oxygen site occupancy disorder. With an increase in the Ba/Sr atomic ratio from 1:1 to 1.7:0.3, the Eu2+ emission band maximum red-shifts from 670 to 775 nm, along with an enlargement of the full width at half-maximum (FWHM) from 140 to 230 nm. The underlying mechanism for the structure–property relationship is elucidated using density functional theory calculations. The application of the NIR phosphor-converted light-emitting diodes (pc-LEDs) is demonstrated, showing their potential in night-vision technology. Our results can initiate further exploitation of the host structural disorder toward Eu2+ broadband NIR luminescence for applications in pc-LEDs.