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Field‐Force Alignment of Disc‐Type π Systems
Author(s) -
Cristadoro Anna,
Lieser Günter,
Räder Hans Joachim,
Müllen Klaus
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600612
Subject(s) - electric field , transmission electron microscopy , perpendicular , materials science , scanning electron microscope , molecule , microscopy , drop (telecommunication) , crystallography , birefringence , anisotropy , optics , nanotechnology , chemistry , composite material , physics , telecommunications , geometry , mathematics , organic chemistry , quantum mechanics , computer science
Abstract The ability of electric fields to align nonpolar semiconducting molecules was demonstrated using hexa(para‐n‐dodecylphenyl)hexabenzocoronene (HBC‐PhC12) as a model compound. A solution of HBC‐PhC12 was applied to a glass surface by drop‐casting and the molecules were oriented into highly ordered structures by an electric field during solvent evaporation. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) showed a long‐range alignment where the disclike molecules were organized in columns perpendicular to the direction of the imposed electric field. The high anisotropy of the uniaxially aligned films was characterized by cross‐polarized light microscopy. The birefringence of the HBC‐PhC12 films was related to the presence of extended domains of unidirectionally aligned columns in which the aromatic cores of the HBC‐PhC12 molecules were perpendicular to the columnar axis. The packing and the arrangement of the molecules in the field‐force ordered films were proven by electron diffraction and X‐ray analyses.