Nitesh Kumar Manoharan, Samuel Paul David, Radhakrishnan Vidya
A series of Pr 3+ -activated Ca 2 YNbO 6 (CYN) double perovskite phosphors was successfully synthesized via the solution combustion method, and their structural, optical, and biocompatibility properties were investigated for solid-state lighting and bio applications. X-ray diffraction (XRD) and Rietveld refinement analyses confirmed that all phosphors crystallize in a monoclinic structure with the P2 1 /n (14) space group. Fourier transform infrared spectroscopy (FTIR) and Raman spectra verified the formation of NbO 6 octahedra, while X-ray photoelectron spectroscopy (XPS) confirmed the + 3 oxidation state of Pr 3+ and the chemical integrity of the host lattice. UV-Vis diffuse reflectance spectra (DRS) indicated a direct bandgap transition with a distinct charge transfer band (CTB) between 200 and 300 nm. Under 450 nm excitation, all Pr 3+ -doped CYN phosphors exhibit intense orange-red emission centered at 660 nm, corresponding to the 3 P 0 → 3 F 2 transition of Pr 3+ . Among different concentrations, 5 % Pr 3+ -doped CYN showed the highest emission intensity with an internal quantum efficiency (IQE) of 36.17 %, demonstrating efficient luminescence. The CIE chromaticity coordinates (0.69, 0.30) and a correlated color temperature (CCT) of 1745 K indicate red emission, which makes it suitable for warm phosphor-converted white LEDs (pc-WLEDs). Pr 3+ -doped CYN also exhibited antibacterial activity against E. coli , while showing no effects on S. aureus . Cytotoxicity studies using L929 fibroblast and HeLa cell lines confirmed excellent biocompatibility at concentrations below 500 µg/mL, with an IC 50 of ∼1239 µg/mL. Distinct intracellular fluorescence in HeLa cells further demonstrated efficient cellular luminescence, verifying its potential for bioimaging. Overall, Ca 2 YNbO 6 :Pr 3+ phosphor is a biocompatible, highly luminescent, and promising candidate for both solid-state lighting and biomedical applications.