Nanowires and nanotubes from π-conjugated organic materials fabricated by template wetting

1D nanostructures (nanowires and/or nanotubes) from poly(9,9-dioctylfluorene-2,7-diyl) (PF8), poly(3-hexylthiophene-2,5-diyl) (P3HT), and N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) were successfully fabricated by a simple and facile template-based technique. The technique involved wetting of porous anodic alumina membranes by solutions and/or melts of the respective materials. Arrays of 1D nanostructures from the polymers PF8 and P3HT can be obtained by both solution- and melt-assisted template wetting. In the case of PF8, the morphology of the obtained nanostructures depends on the wetting conditions: for diluted PF8 solutions mostly nanotubes are obtained; while for concentrated PF8 solutions and PF8 melts, the formation of nanowires is dominating. Wetting of the template pores by P3HT solutions and melts leads to the formation of nanotubes. For the small-molecule material PTCDI-C8, arrays of nanowires can only be obtained by melt-assisted wetting. Wetting of the template pores with PTCDI-C8 solutions does not allow the formation of pronounced 1D nanostructures. For all three materials, the diameters of the formed nanowires and nanotubes correspond to those of the template pores (around 250 nm), while their lengths range from hundreds of nanometers to tens of micrometers. The photoluminescence spectra of the as-prepared nanostructures show peak shifts and redistribution of the peak intensities, if compared to unstructured thin films from the respective materials.