| Research Abstract |
The construction and immobilization π-conjugating and/or δ- conjugating nano-scale architectures on a solid surface or electrode are of current interest for the design and fabrication of microcircuits, microelectronics, and micro-photonics. For example, π-conjugating dots, rods, and discs at nanometer scale on surfaces are widely and intensively studied as models of zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) conjugating systems, respectively. From the viewpoint of semiconductor physics, these 0D-, 1D-, and 2D-systems may be regarded as soft-matter-based quantum dots, wires, and wells. Among the several π-conjugating nano-architectures, nano-ring structures are particularly fascinating as they may serve as an ideal circular 1D-system confined into a well-defined 2D-electronic system with a controlled diameter. Organizing these nano-rings onto a surface in a controlled manner, however, is very challenging; examples of nano-rings arrayed by a bottom-up approach
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remain very rare.
Nano-ring semiconductors are of particular interest because of their potential quantum coherence with external magnetic fields and photons. Organic semiconductors with ring systems may be achieved by two approaches. One is the tailored synthesis of cyclic conjugating molecules. The other is the self-assembly of building blocks by solution casting or vacuum deposition. Synthetic molecules, however, require a multi-step synthesis and usually offer smaller rings with diameters of several nm. Self-assembly are known to be a powerful technique to produce diverse patterns in a wide scale range and from relatively simple manipulation. Here we investigated a facile formation of nano ring architectures of polysilane, polyfluorene, and phthalocyanine on sold substrate surfaces. AFM investigation of these polysilane, polyfluorene, and phthalocyanine verified that isolated rings having diameters within a relative narrow distribution of several hundreds nm are reproducibly formed on mica by simple drop-cast and evaporation procedures. Less
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