Tunable broadband near-infrared emission from environmentally friendly Fe3+-activated lead-free perovskites for spectral analysis and rapid nighttime recognition

With the increasing role of near-infrared (NIR) light sources in many fields such as food and industry, NIR emitting phosphors have flourished in recent years. In addition to the widely reported Cr3+-activated NIR phosphors, environmentally friendly Fe3+ can also produce tunable broadband NIR spectra, which are expected to enrich the next generation of intelligent NIR light sources. In this work, a series of Fe3+-activated perovskite-type Sr2ScSbO6 (SSSO) NIR phosphors were successfully prepared and an emission wavelength of 900 nm with a full width at half maximum (FWHM) of 110 nm was obtained. Through the crystal field engineering strategy, the lattice site of Sr2+ was completely replaced by Ba2+ and Ca2+ to obtain Ba2ScSbO6 (BSSO) and Ca2ScSbO6 (CSSO), and the emission peak was continuously adjusted from 840 nm to 950 nm. When the temperature increased from 300 K to 400 K, BSSO:Fe3+, SSSO:Fe3+ and CSSO:Fe3+ could maintain 69 %, 82 % and 67 % of the original luminescence intensity, respectively. The opposite crystal field dependence between Fe3+ and Cr3+ was shown in double-layer perovskite-type antimonate materials, which could guide us to develop Fe3+-activated long-wavelength emission NIR phosphors. Benefiting from the long-wavelength emission of BSSO:Fe3+, SSSO:Fe3+, and CSSO:Fe3+, their application potential in the field of spectral analysis and rapid nighttime recognition were successfully demonstrated.