Investigation of liquid-crystalline behaviour of copper octakisalkylthiophthalocyanine and its film properties

The mesogenic properties of copper octakisalkylthiophthalocyanine [(C6S)8PcCu] were studied by differential scanning calorimetry (DSC), X-ray and optical microscopy. This phthalocyanine forms columnar hexagonal (Colh) mesophase. Thin films of (C6S)8PcCu were prepared by spin-coating technique. Thermally induced molecular reorganization within the films was studied by the methods of ellipsometry and UV–Vis absorption spectroscopy. Heat treatment produces molecular ordering which is believed to be due to stacking interaction between neighbouring phthalocyanine moieties. The differences in structural organization of the heated and unheated films were stated. These differences in structural organization in their turn are found to influence the electrical properties of the films.