Growth, Alignment And Patterning Of One-Dimensional Organic Nanostructures

Organic one-dimensional (1D) nanomaterials based on low-molecular-weight semiconducting compounds have been demonstrated to possess unique properties that can be an effective alternative to carbon nanotubes and inorganic 1D nanostructure used in nanoscale optoelectronic devices. Many organic materials and methods were employed to synthesize 1D single crystalline nanostructures of organic semiconductors. Although there are several approaches to directly fabricate organic 1D single crystal on specific device platforms, it is more useful and critical to make aligned 1D nanostructures and pattern on a substrate for device fabricating. However, very few aligned organic 1D nanostructures and their patterning techniques were reported and they were always complicate and needed assistance from templates, external field or surface-invasive steps. Here, we report two simple methods for growth, alignment and patterning of one-dimensional organic nanostructures. Firstly, single crystalline squaraine dye nanowires are synthesized by solvent evaporation at the dichloromethane/water interface and then self-aligned into ordered ultrathin film driven by the compressed force from the reduced liquid-liquid interface. The ultrathin film can be easily transferred onto desired solid substrate or stacked to form multilayered structures by layer-by-layer technique for device application. The simple one-step approach was confirmed to be applicable for other organic materials. Devices based on the ordered nanowire films exhibit strong photo response characteristics with excellent stability and repeatability. This suggests that this low-cost process for producing films of aligned organic nanowires over large areas can be useful for future large-scale applications of organic nanostructures.Secondly, single-crystal squaraine dye nanowires are prepared on solid substrates by solvent evaporation. The nanowires can self-assemble into aligned arrays and patterns on substrates in periodic rings or parallel stripes as a result of combined molecular self-assembly, contact-line pinning and dewetting. This simple one-step method for growth and patterning of aligned organic nanostructures would facilitate easy and low-cost fabrication of organic devices with one-dimensional nanostructures, especially for the fabrication of parallel arrays of devices. In addition, we have also confirmed that the method can be applicable to other organic compounds.