Structural and optical properties of 1, 4, 8, 11, 15, 18, 22, 25-octahexylphthalocyanine: A comparison between thermally evaporated and spin-coated thin films

Abstract

Thin films of 1, 4, 8, 11, 15, 18, 22, 25-octahexylphthalocyanine were deposited on glass substrates by the thermal evaporation and spin coating techniques. The structure of the both types of films was found to be in α form. The crystallite size assumed the values of 88.65 and 44.32 nm for thermal and spin coated films, respectively. The surface morphology of the thin films was investigated by atomic force microscopy and showed that the molecules of 1, 4, 8, 11, 15, 18, 22, 25-octahexylphthalocyanine grew in stacks of parallel rows. The optical properties of thermally evaporated and spin coated films are reported here. The spectrophotometric measurements of transmittance and reflectance were carried out at UV–Vis–NIR region for the films that showed two absorption bands, namely the Q-and Soret bands. The mechanism of the optical absorption follows the indirect transitions. Almost there was no remarkable difference was observed between the two types of films. Other optical parameters, such as absorption coefficient α, the absorption index, k, and refractive index, n, were also determined.