Hexa-peri-benzocoronene (HBC) is a nanoscale version of an infinite 2D graphene sheet soluble in organic solvents. The interest in molecular electronics on these derivatives is due to their high charge carrier mobilities (0.13 cm2/Vs). Our interest is focused on the possibility to use the well-known p-p stacking to produce columnar aggregates of this species.
We report on the growth of highly ordered layer architectures from solutions. We show how Tapping Mode - Scanning Force Microscopy and angle-resolved photoemission measurements can be used complementary to gain insight into the molecular order in organic dry thin films.
It is found that this disc-like molecule grown on a conductive solid flat substrate like highly oriented pyrolitic graphite (HOPG) can self-assemble into monolayers with the p-conjugated disc like system lying preferentially flat on the basal plane of the substrate. Varying the procedures of the film preparation from solution it was possible to tune the rate of the molecular self-assembly. At very slow deposition speeds we succeed in producing layers aligned preferentially along the crystallographic axes of the HOPG substrate. This suggests that the growth of this molecular systems on solid substrates is a kinetically governed process which on a crystalline support in equilibrium leads to a hetero-epitaxial type of growth on a crystalline support.