Understanding Metal-Directed Growth of Single-Crystal M-TCNQF4 Organic Nanowires
K. Xiao, M. Yoon, A. J. Rondinone, E. A. Payzant, and D. B. Geohegan
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
Combined experimental and theoretical studies revealed the nucleation and growth mechanisms of M-TCNQF4 crystalline organic nanowires grown on different metals by vapor-solid chemical reaction (VSCR). Real-time x-ray diffraction was used to measure the growth kinetics of the nanowires, and a modified Avrami model of the data showed that growth proceeds via a 1D ion diffusion-controlled reaction at their tips. First principles atomistic calculations were used to understand how charge transfer interactions govern the reactivity of different metals in the growth process through the extraction and integration of metal ions from the substrate into the nanowire, and their diffusion to the tip where they react with incoming molecules to continue the growth process.
This work provides fundamental understanding of the growth mechanism how metals direct the assembly of small molecules into organic nanowires and what determines the selectivity of a metal for an organic vapor reactant in the VSCR process. Understanding how to control the VSCR growth process will enable the synthesis of novel organic nanowires with axial or coaxial p/n junctions for organic nanoelectronics and solar energy harvesting.
This work will be published in Journal of American Chemical Society (doi: 10.1021/ja301456p). This research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy.