Molecular Orientation and Electrical Properties in tert-Butylated Phthalocyanine Thin Film Fabricated by Uniaxial Solution Coating

Abstract

Molecular orientation, molecular packing structure, and electrical properties of thermally stable phthalocyanine, tert-butylated phthalocyanine (t-BuPcH₂) in the thin film fabricated by bar-coating method were investigated. The XRD patterns indicated that the columns composed of t-BuPcH₂ molecules formed hexagonal structure, the axis of which was parallel to the bar-sweep direction, and t-BuPcH₂ molecules were vertically aligned to the bar-sweep direction. Uniaxially oriented thin films of t-BuPcH₂ were successfully fabricated on Si substrate covered with polyimide by bar-coating method, and the field effect mobility of t-BuPcH₂ was estimated to be 1.32×10^-4 cm² V^-1 s^-1 at maximum. The field effect mobility parallel to the bar-sweep direction was approximately three times higher than that perpendicular to the bar-sweep direction due to high electrical conduction along the column axis of t-BuPcH₂.