Molecular orientation of copper phthalocyanine thin films on different monolayers of fullerene on SiO_2 or highly oriented pyrolytic graphite

摘要

The interface electronic structures of copper phthalocyanine (CuPc) have been studied using ultraviolet photoemission spectroscopy as different monolayers of C_(60) were inserted between CuPc and a STO_2 or highly ordered pyrolytic graphite (HOPG) substrate. The results show that CuPc has standing up configuration with one monolayer of C_(60) insertion on SiO_2 while lying down on HOPG, indicating that the insertion layer propagates the CuPc-substrate interaction. Meanwhile, CuPc on more than one monolayers of C_(60) on different substrates show that the substrate orientation effect quickly vanished. Our study elucidates intriguing molecular interactions that manipulate molecular orientation and donor-acceptor energy level alignment.