Thin layers of columns of an amphiphilic hexa-peri-hexabenzocoronene at silicon wafer surfaces

We present here the preparation and the structures of thin films of an amphiphilic hexa-peri-hexabenzocoronene (HBC) containing 1, 5, 9, and 15 layers of columns. These films were prepared by the Langmuir-Blodgett technique on poly(ethylene imine) functionalized silicon wafers and investigated by X-ray reflectivity measurements using synchrotron radiation. Columns of HBC cores were aligned parallel to the silicon wafer surface. The thicknesses of the films, which were composed of stacks of highly coherent HBC layers plus a polymer layer, were 3.70-34.6 nm. Each HBC layer has a thickness of 2.4 nm. The transfer rate of the HBC monolayers from the water/air surface to the silicon wafer surface is close to 100%. A macroscopic in-plane orientation of the columns with their main axis parallel to the dipping direction was determined by polarized UV-vis spectroscopy.