Bright White Light Emission by Nanopowders and Thin Films of PrO2:Zr-Based Materials Excited at the Near-Infrared

Doped nanoparticles of Pr1-x Zr x O2 (x = 0.05, 0.10 (PZ10), 0.20, and 0.3) were successfully synthesized via the Pechini method. These particles retained the cubic structure of PrO2, with lattice parameters and energy bandgaps varying linearly with the amount of Zr4+ (x in Pr1-x Zr x O2). The absorbance at 980 nm decreased linearly with the nanoparticle diameter, attributed to ligand-to-metal charge transfer (LMCT) states related to the concentration of [Pr4+-O2-] pairs near the surface. These nanopowders exhibited bright white light emissions under near-infrared (NIR) excitation (980 nm) at power densities from 80 to 200 W cm-2. The emission spectra showed a continuous broadband, typical of a blackbody-type exitance. The integrated emission intensity and fitted temperature notably demonstrated linear correlations with the absorbance and excitation power density, respectively. Using a thermal camera, we determined the exitance coefficients of these nanopowders. For practical applications, thin films of PZ10 and PrO2 deposited on transparent substrates maintained bright white emissions under both atmospheric and vacuum conditions, which were employed as possible pressure-sensing devices. These findings are significant for designing efficient materials, offering the potential for testing and validating quantitative models that explain this phenomenon and for improving solar cells and photocatalytic systems.