Figure 2.

Comparison of the molecular arrangement in the two polymorphs of PFP determined in this work. (a) Herringbone arrangement of the TFP on SiO_x viewed along the long molecular axes (left), illustrated within the unit cell (middle), and as a top view on the (100) texture plane^37,38 (i.e., along the a* axis) (right). (b) π-Stacked arrangement of the PSP viewed along the long molecular axes (left), within the unit cell (middle), and as a top view on the (001) texture plane parallel to graphene (i.e., along the c* axis) (right). Similar π-stacked motifs are shaded in red; π-stacking distances are indicated. (c) Calculated atomic charges on the constituting atoms of a PFP molecule. (d) Calculated molecular electrostatic potential map (in atomic units) of an individual PFP molecule with an adjacent molecule within the parallel-displaced stacked motif of the PSP.