Abstract
We studied gas-exposure effects on pentacene (Pn) films on and Au(111) substrates by ultrahigh sensitivity photoelectron spectroscopy, which can detect the density of states of states comparable to electrical measurements. The results show the striking effects for : exposure to inert gas ( and Ar) produces a sharp rise in gap states from to states and pushes the Fermi level closer to the valence band (0.15–0.17 eV), as does exposure to (0.20 eV), while no such gas-exposure effect is observed for . The results demonstrate that these gap states originate from small imperfections in the Pn packing structure, which are induced by gas penetration into the film through the crystal grain boundaries.
- Received 13 February 2013
DOI:https://doi.org/10.1103/PhysRevLett.110.267602
© 2013 American Physical Society