Sultan Moulay Slimane University, Morocco
Rare-earth ions RE 3+ co-doped nano-materials have attracted much attention due to their physic-chemical resistance, photoluminescent properties, and various applications such as biomedical labels, plasma display panels, electrical conduction, fluorescent lamps, and solar cells. In recent years, considerable attention has been paid to the downconversion (DC) process in LnPO4 (Ln = La, Y, Ce, or Gd) compounds for improving the efficiency of solar cells, which is important for environmental reasons. The phosphors LaPO4 (Lanthanum phosphate) co-doped with RECe3+ were effectively synthesized by direct precipitation method using nitrates and phosphate solutions as starting materials. The prepared samples were characterized by powder X-ray diffraction (XRD) to confirm the formation of LaPO4 nanoparticles with crystal structure monoclinic P21/n and surface morphology was studied by scanning electronic microscope (SEM). Additionally, Fourier transforms infrared spectroscopy (FTIR) and thermogravimetric/differential thermal analysis (TG-DTA) were investigated to prove the phosphate vibration bands and the temperature of total dehydration of the rhabdophane phase, respectively. The photoluminescence (PL) properties of samples in ultraviolet-visible (UV– VIS) and near-infrared (NIR) regions were investigated to verify the energy transfer (ET) process from donors to acceptor ions. Down-shifting and near-infrared (NIR) quantum cutting involving the downconversion in Ce3+ -RE3+ co-doped LaPO4 phosphors can convert a photon of the UV region (approx. 290 nm) into photons of the NIR region through several electronic transitions. Indeed, the tested dopants can be employed as important NIR luminescence RE 3+ ions with typical emission peaks, meet the strongest spectral response of c-Si solar cells, and Ce3+ ion might be an ideal broadband sensitizer for the used RE3+.