• • Mn2+-doped MIn2S4 (M = Sr, Ba) phosphors exhibit ultrawideband deep-red to NIR emission spanning 600–850 nm with FWHM of 123–257 nm, enabling superior spectral coverage for biomedical imaging and plant lighting.
• • The emission wavelengths of 700–720 nm in these sulfides are significantly longer than those of other Mn2+-doped sulfide phosphors, attributed to the combined effects of strong nephelauxetic effect and strong crystal field from distorted polyhedra.
• • BaIn2S4:Mn2+ shows inhibited energy transfer between sites due to single luminescence centers, significantly enhancing its luminescence efficiency, which is critical for high-brightness pc-LED applications.
• • The excitation band of BaIn2S4:Mn2+ matches well with commercial 365 nm NUV chips, and its luminescence color exhibits superior thermal stability, underscoring its strong potential in biological imaging and solar-like lighting.