Using atomic force microscopy to reveal the nature of extended defects in organic semiconductors: The role of crystal growth mechanisms

Abstract

Optical and atomic force microscopy measurements on the 001 form of the organic semiconductor quaterthiophene revealed interlaced spiral patterns arising from growth layers mutually rotated by 180° about the normal to the (001) crystal face. This bulk-surface relationship, along with the height of the exposed step ledges of the order of 10-100 nm, evidences the complex polytypic nature of these crystals in which the basic P21/c layer gives rise to several different stacking along [001], even within the same crystallite. The consequences on solid state physical properties arising from these crystal growth phenomena are briefly discussed. © 2007 IOP Publishing Ltd.