Compositional modulation induced broadband NIR luminescence enhancement in A2ScNbO6:Cr3+ (A = Ba, Sr)

•A NIR emission at 890 nm with 200 nm FWHM is realized in Ba2ScNbO6:Cr3+ phosphor.•The modulation of the host bandgap by turning composition enhances the NIR emission.•The structure-property relationship provides insights for new broadband NIR phosphors. To fulfill the near-infrared (NIR) spectroscopy application in portable and appropriately sized equipment, it is necessary to develop novel NIR pc-LEDs that are fabricated from high-efficiency broadband NIR phosphors. Herein, a series of Cr3+ doped double perovskite type A2ScNbO6:Cr3+ (A = Ba, Sr) phosphors with an emission peaked around 890 nm and full width at half-maximum greater than 200 nm are developed. By replacing Ba with Sr in the host composition, the NIR emission intensity under near ultraviolet (NUV) excitation is significantly enhanced without narrowing the emission bandwidth. The underlying mechanism is investigated in detail by structural analysis, spectral analysis and density functional theory calculations, revealing a strong correlation with the introduction of Sr in terms of changes in the host bandgap and electron-phonon coupling effects. The compositional modulation strategy has unveiled the structure-property relationship in Cr3+ doped double perovskite, shedding new light on guiding the development of broadband NIR phosphors. [Display omitted]