Optical and dielectrical properties of azo quinoline thin films

摘要

In this study, the optical and dielectrical properties of a novel series of quinoline azodyes (5-(4'-de-rivatives phenyl azo)-8-hydroxy-7-quinolinecarboxaldehyde) (AQL_1- AQL_5) were investigated and the obtained results were analyzed. The X-ray diffraction (XRD) patterns of AQL_n show that the materials in the powder form are a mixture of amorphous and crystalline structure, while the thermally deposited thin films are completely amorphous. The optical constants such as the refractive index, n, the absorption index, k and the absorption coefficient, α, were determined using spectrophotometric measurements of transmittance (T) and reflectance (R) in the wavelength range 200-2500 ran. According to the single oscillator model (SOM), some related parameters such as oscillation energy (E_o), the dispersion energy (Ed), the optical dielectric constant (ε_∞,), the lattice dielectric constant (ε_l) and the ratio of free carrier concentration to its effective mass (N/m~*) are estimated. The emission spectra of azo quinoline ligands (AQLn) exhibit dual fluorescence peaks in the region 512-580 nm. This finding reveals the formation of two stoichiometric hydrogen-bonding in the ground and excited state. The dielectrical properties and alternating current conductivity (σ_(ac)) are investigated in temperature range 298-483 K and frequency range 0.1-100 KHz.