Fabrication and Characterization of Anthracene Doped P-terphenyl Thin Films By Spin Coating Technique; Investigation of Fluorescence Properties

Thin films of p-terphenyl luminophors doped by varying amounts of anthracene were prepared by using spin coating technique. The morphological, structural, and photophysical investigation of thin films of p-terphenyl as a function of anthracene concentration is studied by using scanning electron microscopy (SEM), X-ray diffraction (XRD), fluorescence spectroscopy and fluorescence microscopy. The results of XRD and SEM studies indicated that the doped p-terphenyl thin film is homogeneous as compared with a bare p-terphenyl thin film. The fluorescence spectroscopy results indicate complete quenching of p-terphenyl fluorescence and simultaneous sensitization of blue anthracene like emission towards the red side of the spectrum with maximum intensity at 410 nm. The blue intense emission of anthracene seen in fluorescence microscopy images is in agreement with observed fluorescence spectral results. A suitable mechanism of excitation energy transfer (EET) from p-terphenyl to anthracene molecules is proposed and discussed on the basis of energy level diagram. The efficient EET is believed to occur by the orientation of phenyl rings of p-terphenyl in excited state. As the concentration of doped anthracene increases, the fluorescence intensity of doped p-terphenyl and Full Width at Half Maximum (FWHM) found to be increased. The p-terphenyl film containing 0.65 moles of anthracene is of FWHM as low as 28.51 nm. Such narrow band blue emitting doped luminophors are of demand in light emitting diodes (OLED) and scintillation applications.