Lawrence Berkeley National Laboratory

We report a "one-step" method for preparing conductive thin films with cylindrical microdomains oriented normal to the surface over large areas using the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS₁₉-b-P4VP₅) and 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (HOTPP). HOTPP interacts with the P4VP block by hydrogen bonding between the hydroxyl group of HOTPP and pyridine ring of PS₁₉-b-P4VP₅, forming cylindrical P4VP(HOTPP) domains having an average diameter of ∼17 nm in a PS matrix. Dynamic light scattering, contact angle, and in situ grazing incidence small-angle X-ray scattering measurements show a morphological transition from spherical micelles in solution to cylindrical microdomains oriented normal to the substrate surface during the drying process. From the dependence of current on voltage, an average current of ∼4.0 nA is found to pass through a single microdomain, pointing to a promising route for organic semiconductor device applications.