Luminescence of 2,6-Distyrylpyridine-Doped Titania Nanostructured Monoliths

Abstract

Nanocrystalline 2,6-distyrylpyridine (2,6-DStP)-doped TiO₂ monoliths were prepared by the sol–gel technique. Different concentrations of the 2,6-DStP doping agent were utilized. Samples were characterized by x-ray diffraction, photoacoustic spectroscopy (optical absorption), and luminescence spectroscopy. As-prepared samples showed amorphous structure and traces of the anatase crystalline phase of TiO₂ after annealing at room temperature. The samples exhibited average particle size from 6 nm to 7.5 nm for molar concentration of 2,6-DStP from 0.0% to 0.03%. The photoacoustic spectra revealed the absorption edge at wavelength around 375 nm (3.38 eV), which is attributed to TiO₂, and a gap shift varying from 1.91 eV, to 2.41 eV, to 1.86 eV with the molar concentration of 2,6-DStP. Photoluminescence spectroscopy showed three different bands around 555 nm, 607 nm, and 779 nm when the samples were excited with 407 nm, 488 nm, and 633 nm laser lines, respectively.