Molecular Packing Structure of Mesogenic Octa-Hexyl Substituted Phthalocyanine Thin Film by X-ray Diffraction Analysis

The molecular packing structure in a thin film of the liquid crystalline phthalocyanine, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH₂), which is a promising small-molecular material for solution-processable organic thin-film solar cells, has been investigated by X-ray diffraction (XRD) measurement. The crystal structure of C6PcH₂ in the spin-coated film was determined to be a centered rectangular structure (a= 36.4Å, b 20.3 Å). The tilt angle of the phthalocyanine core normal vector was 34–39° from the column axis, and the shortest intermolecular distance was 3.9–4.0 Å. The crystal structure determined by XRD analysis was ascertained to be consistent with that calculated by Fourier analysis.