2023 Fall Meeting of the APS Eastern Great Lakes Section
Friday–Saturday, October 20–21, 2023;
Cleveland State University, Cleveland, Ohio
Session F01: Poster Session
5:30 PM,
Friday, October 20, 2023
Cleveland State University
Room: Fenn Tower 303
Abstract: F01.00056 : Chatacterizing Pentacene Thin Film Growth on HOPG*
Abstract
Presenter:
Grace M Miller
(Cleveland State University)
Authors:
Grace M Miller
(Cleveland State University)
Jessica E Bickel
(Cleveland State University)
Organic electronics are generally more cost effective and environmentally friendly compared to their inorganic counterparts. However, organic materials often have an amorphous structure that makes them less conductive and less efficient in electronics. Their conductivities can be improved by creating crystalline films, which makes the distance between adjacent molecules uniform and allows for easier electron movement between adjacent molecules. One method for crystallizing organic materials is self-assembly on atomically ordered surfaces. In this work, Pentacene is thermally evaporated onto Highly Oriented Pyrolytic Graphite (HOPG) using a line-of-sight evaporation method. The resulting films are characterized by Scanning Tunneling Microscopy (STM) with the goal to determine ideal pentacene parameters for thin-film evaporation. While most trials tended to have disorganized depositions, we observed pentacene forming organized structures in two trials. In the first, we observed a honeycomb structure with a periodicity of 9.4nm. We compared the unit cell spacing to the dimensions of both a single pentacene molecule and pentacene's general triclinic crystal structure but neither fit our sample. A second organized trial showed a slightly smaller repeating pattern along a step edge with a spacing of 4.4nm. While not crystalline, this structure was periodic in the single dimension of the step edge. This structure was only compared to a single pentacene molecule, as the structure was a similar height to a monolayer of pentacene, but again the values do not quite match our structure. We were unable to reproduce either of these trials, largely due to our Quartz Crystal Monitor (QCM) giving inaccurate growth rates and thicknesses. Being able to reproduce these structures and determine more refined deposition parameters for which they form is essential to learn more about how pentacene is forming on the substrate. While we were unable to determine exactly how the pentacene molecules were forming on the substrate, our work shows pentacene's ability to form organized structures.
*USRA fundedĀ