Structural and photoluminescent investigations of SrAl2O4:Eu[formula omitted],RE[formula omitted] improved nanophosphors for solar cells

Abstract

The long afterglow green emitting materials were prepared by fast gel-combustion procedure (600 °C) using urea as fuel. This paper reports the improvement in photoluminescence intensity and persistency of Eu2+ incorporated long-persistent SrAl2O4 nanophosphors by the addition of rare earth ions (Dy3+, Pr3+, Y3+) as codopants. The materials were investigated using X-ray diffraction (XRD), Fourier transformation infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. X-ray diffraction analysis exhibited the formation of pure SrAl2O4 phase with monoclinic crystal system and space group P21. FTIR spectra were used to determine the stretching and bending modes of vibrations to confirm the formation of metal–oxygen bonds. The microstructures were observed using SEM and TEM analysis. For the synthesized strontium aluminate phosphors, the photoluminescence characteristics including excitation, emission and decay kinetics were also examined. PL emission spectra, recorded at the excitation wavelength of 362 nm, exhibited the characteristics peak at 510 nm corresponding to the parity allowed 5d–4f electronic transition of Eu2+ ions. The phosphorescence intensity of the materials were greatly enhanced on addition of codopants (Dy3+, Pr3+, Y3+), without any change in the position of the peak in spectra. The outcomes of these investigations made the focused materials worthy for the applications in the solar cells and lighting technology.