Determination of the Lowest Energy Orientation of Pentacene on Graphene

Organic semiconductors are advantageous over their inorganic counterparts due to their eco-friendliness, cheap producibility, and applications in flexible electronics. However, organic semiconductors tend to have a lower conductivity than their inorganic counterparts. One method to increase the conductivity of organic semiconductors is self-assembly driven by a surface reconstruction. As an atomically smooth surface is needed to organize organic molecules, a possible starting point is to examine the deposition of an organic molecule on graphene or graphite. This work utilizes computational calculations run in parallel to experimental growths to examine how pentacene self-organizes on graphite. The computational experiments were done with the Vienna Ab initio Simulation Package (VASP) where molecules were both translated and rotated to find the lowest energy orientation of pentacene on a graphene sheet. These results are compared to experimental results of pentacene deposited on highly ordered pyrolytic graphite (HOPG) and examined via scanning tunneling microscopy (STM).