Binary Systems of Discotic Liquid Crystalline Semiconductors toward Solution-Processing Thin Film Devices

Binary mixtures of a phthalocyanine (Pc) mesogen and its Zn complex, which have eight decyl chains at the non-peripheral positions of Pc were studied as an organic semiconducting system. The complete miscibility was observed for the Col(h) mesophase and the carrier mobility for the Col(h) mesophase was measured to give small decrease of mobility in the 1:1 mixture in comparison to that of the pure compounds. These indicate that in this binary system, two compounds could mostly behave as the identical molecules and no specific interaction was expected. The different component ratio affects the carrier mobility depending on the ratio, meaning the molecular dispersion is not taken place in a monomolecular level and possibly columns formed by each compound exist to hold a certain distance for successive charge hopping. These results indicate that the mixture of mesogens could make mesogenic systems useful for new applications such as organic thin film solar cells.