Tunable Broadband Red-To-Near-Infrared Emission in Eu(2+)-Activated Sr(1-x)Ba(x)La(2)Sc(2)O(7) Phosphors via Site-Selective Occupation and Cation Substitution.

In this work, a series of Eu-doped SrLaScO phosphors were rationally designed and synthesized, exhibiting high photoluminescence quantum yields and excellent thermal stability. Under 440 nm blue-light excitation, these phosphors show a broad red emission band centered at 613 nm, with a full width at half-maximum (fwhm) of 81 nm (corresponding to ∼0.26 eV at ∼613 nm). By employing a Sr/Ba substitution strategy to modulate the local crystal field around Eu, both a redshift in the emission peak and significant spectral broadening were achieved. Notably, complete substitution of Sr with Ba yielded a BaLaScO:0.015Eu phosphor that exhibits a broadband near-infrared (NIR) emission peaking at 812 nm with an ultrabroad fwhm of 318 nm (corresponding to ∼0.59 eV at ∼812 nm). Moreover, aliovalent substitution of Eu for Sc generates oxygen-vacancy-related defect centers that act as carrier traps, extending the emission lifetime and enhancing resistance to thermal quenching in SrLaScO:0.015Eu. In addition, incorporation of larger Ba ions softens the host lattice, strengthening excited-state lattice relaxation and electron-phonon coupling, thereby increasing the Stokes shift and further broadening the Eu emission band to realize tunable broadband red-to-NIR emission in Eu-activated SrBaLaScO phosphors. These findings broaden the family of Eu-activated scandate oxide phosphors and provide a viable strategy for tuning broadband NIR emission via targeted cation substitution devices.