Employing x-ray spectromicroscopy for the understanding of anisotropy in organic thin film growth

We report on the fabrication of high-quality organic semiconducting thin films from the potent benchmark molecular compounds pentacene and C8-BTBT-C8. For organic films prepared by the floating-lens method, we observe 1D anisotropy in linear NEXAFS dichroism. Based on the molecular orientation contrast in scanning transmission x-ray microspectroscopy (STXM), azimuthal sample rotation and AFM, we can confirm a high degree of long-range molecular order. The experimental results allow for deeper insight into the presumed growth behavior, which appears to crucially depend on the nature, or more specifically, the aromaticity and volatility, of the used solvent.