Broadband near infrared emission in Cr3+: Cs2AgBiCl6 double perovskite halides

Near Infra-red phosphors with broad emission band, high thermal stability and excellent efficiency are required in various bioimaging applications. In this study, we report the design and chemical reflux synthesis of a new family of Cr3+: Cs2AgBiCl6 double perovskites. In detail this article focuses on the impact of Cr3+ doping on the crystal structure, optical and vibrational properties of Cs2AgBiCl6 double perovskites. Different concentrations of Cr3+ doped Cs2AgBiCl6 double perovskites were analyzed using UV–Visible, Raman, Photoluminescence (PL), PL excitation, time resolved PL, X-ray photoelectron spectroscopy. Morphological analyses were carried out using scanning and transmission electron microscopies. XRD spectra reveals that the cubic symmetry remains unaltered upon Cr3+ doping. Raman and Rietveld analysis show that the Bi–Cl bond decreases upon Cr3+ incorporation. Optical absorption studies reveal a decrease in bandgap from 2.76 to 2.66 eV upon Cr3+ doping. PL spectroscopy of Cr 3+:Cs2AgBiCl6 exhibits a broad near infrared (NIR) emission band at 973 nm with an FWHM of 186 nm at 355 nm excitation. This demonstrates the promising prospects for NIR light emitting diode and bioimaging applications of Cr3+:Cs2AgBiCl6 double perovskites.