Preparation of phthalocyanine ultrathin film via layer-by-layer assembly

Phthalocyanine ultrathin films were prepared by a successive dip/dry process of hydroxy-group-bearing substrates into a dilute solution of phthalocyanine with silanol group at its coordination center (Pc). Amounts of adsorbed Pc on the substrate were monitored using a quartz crystal microbalance. At each dip/dry cycle, the adsorbed Pc corresponded to the mass of a single Pc layer flat on the surface. On the other hand, similar results could not be achieved with a pre-polymerized Pc, which showed Langmuir-type adsorption onto the substrate, probably due to the forming of a horizontally aligned monolayer. The Pc ultrathin film was specifically formed on an n-hexanol-presented substrate, although the Pc ultrathin films could not be formed with shorter ethanol- or longer undecanol-presented substrates. Furthermore, a hetero-structured Pc ultrathin film was prepared using an alternative second component Pc.