Paper SS-TuP1
Self-assembly of Organic Thin Films on Metal Surfaces

Tuesday, October 31, 2017, 6:30 pm, Room Central Hall

Organic semiconductors have the potential to replace silicon in some electronic devices because they require less stringent production environments and can offer new functionalities, such as flexible devices. One major drawback of organic semiconductor films is their inefficient charge transport. In traditional organic film materials, the molecules only lay flat in the first few molecular layers before transitioning to less favorable geometries for charge transport. Previous work published in our group has shown that the tris(N-phenyltriazole) (TPT) molecule on a Ag(111) surface shows planar stacking through more than 20 molecular layers due to the π-π donor-acceptor intermolecular contacts between the electron-deficient tris(triazole) core and electron-rich peripheral phenyl units. Scanning tunneling microscopy (STM) studies of this molecule show that it does not change its packing structure through the >20 molecular layers studied. Here, we present investigations of derivative molecules of TPT which have different electron distributions and structures to investigate their effect on stacking. We compare the monolayer packing of these derivative molecules to that of TPT by molecular-resolution STM analysis and then investigate multilayer stacking properties of these molecules. Comparison conductivity measurements for TPT, and the two derivative molecules are compared with pentacene using four-point conductivity measurements. These studies may lead to new organic semiconductor material designs that have well-controlled structure and increased charge transport, making them more competitive with traditional silicon devices.