One-Step Dry Method for the Synthesis of Supported Single-Crystalline Organic Nanowires Formed by π-Conjugated Molecules

Abstract

We present for the first time a general vacuum process for the growth of supported organic nanowires formed by pi-conjugated molecules, including metalloporphyrins, metallophthalocyanines, and perylenes. This methodology consists on a one-step physical vapor deposition of the pi-conjugated molecules. The synthesis is carried out at controlled temperature on substrates with tailor morphology which allows the growth of organic nanowires in the form of squared nanofibers and nanobelts. The study of the nanowires by electron diffraction and HRTEM combining with the results of a theoretical analysis of the possible arrangement of the pi-conjugated molecules along the nanowires reveals that the nanowires show a columnar structure along the fiber axis consisting of pi-stacked molecules having a herringbone-like arrangement. The formation of these nanowires on different substrates demonstrates that the growth mechanism is independent of the substrate chemical composition. An in-depth phenomenological study of the formation of the nanowires drives us to propose a growth mechanism based on a crystallization process. Furthermore, the growth method allows the fabrication of two particular 1D heterostructures: binary and open core@shell organic nanofibers.

Self-Assembly of the Nonplanar Fe(III) Phthalocyanine Small-Molecule: Unraveling the Impact on the Magnetic Properties of Organic Nanowires

“…This arrangement is characteristic of the phthalocyanines' triclinic crystal structure. 14,15,30,31 Furthermore, in the FePc SAED diagram we note an intensity increase of the diffraction dots corresponding approximately to the (210) direction and also a minor one on the (310) direction. These effects could be attributed to the herringbone angle of the molecular arrangement which would be oriented to this direction (i.e., between 20°(210) and 28°(310) from the intercolumn direction).…”

“…These effects could be attributed to the herringbone angle of the molecular arrangement which would be oriented to this direction (i.e., between 20°(210) and 28°(310) from the intercolumn direction). 15 A similar case occurs in the FePcCl SAED diagram, where the interplanar stacking direction is at 87°from the intercolumnar direction. In this case, the diffraction intensity increase is located between the (100) and the (200) (i.e., between 15°and 20°), presenting approximately a similar increase in both cases.…”

“…The TEM analyses let us determine both the column spacing between the molecules on a single nanowire and the intermolecular spacing and relative orientation of the characteristic herringbone structure resulting from the molecular self-assembly. 15 The nanowires were scraped from the Al/Si(100) substrates and deposited on gold grids for the TEM analysis. Energy-dispersive X-ray (EDX) spectra were recorded during the TEM measurements, and estimates of the Fe/Cl ratio EDX profiles were acquired with a FEI Tecnai Osiris TEM/STEM 80-200 working at 200 kV.…”

“…These molecules self-assemble into supported single-crystal nanowires tens of nanometers in width and several micrometers in length. 14,15,18 Such a heterogeneous crystallization process can be enhanced by including nucleation centers at the substrate to trigger the preferential condensation of molecules on those spots. 14,15 Formation of ONWs has been reported during the last years on an ample variety of surfaces including metal and metal oxide thin films and organic supports.…”

High carrier mobility of CoPc wires based field-effect transistors using bi-layer gate dielectric

“…Therefore, the molecules are ideal building blocks for the growth wire like structures by selfassembly via π -π stacking. 18,19 In this work, we have used CoPc wires as the channel materials. Due to high crystallinity, these wires show better charge transport properties.…”