Dependence of Optical Properties of Safranin-T Films on Post-deposition Annealing Temperature

Thin films of Safranin-T have been deposited using an evaporation technique. Infrared spectra demonstrated that the evaporation method is effective to obtain undissociated Safranin-T films. Scanning electron microscopy and x-ray diffraction analysis revealed that the Safranin-T films had amorphous structure, which transformed to nanocrystalline after annealing. The optical properties of the nanostructured Safranin-T films were measured. Two indirect allowed optical bandgaps with values of 1.83 eV and 3.58 eV were found from the absorption coefficient of the as-deposited film, decreasing to 1.41 eV and 2.11 eV after annealing at 300A degrees C. The single-oscillator model was applied to investigate the dispersion of the refractive index and calculate the dispersion parameters as functions of annealing temperature. Some nonlinear optical parameters were also calculated for different annealing temperatures.