GdPO4:Eu3+ nanoparticles with intense orange red emission suitable for solar spectrum conversion and their multifunctionality

Gadolinium orthophosphate nanoparticles doped with Eu3+ have been successfully synthesized by co-precipitation in alkaline environment. As synthesized hexagonal GdPO4:Eu3+ nanoparticles (~10 nm) transform to monoclinic nanocrystals in 20-50 nm size range and 100-200 nm size range upon annealing at 800 °C and 1000 °C respectively. Monoclinic nanocrystals show intense orange emission around 593 nm due to radiative transitions from 5D0 to 7F1 triplet Stark split levels of Eu3+ as the most prominent group with estimated splitting of 17.71 and 11.33 meV between Stark levels. The excitation range covers 250-400 nm with maximum absorption at 395 nm due to f-f transitions of Eu3+. The nanoparticles can efficiently convert UV and violet photons, available in terrestrial solar spectra, to intense orange and red light that can be harnessed by Si solar cells for photovoltaic conversion. Further, Gd in the host makes the luminescent GdPO4:Eu3+ nanoparticles highly paramagnetic rendering multifunctionality.