Supramolecular architecture of organic molecules: PTCDA and CuPc on a Cu(1 1 1) substrate

We report on the molecular self-assembly of a highly ordered mixed molecular structure of copper-phthalocyanine (CuPc) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) on Cu(1 1 1) starting from dense PTCDA domains. Low temperature scanning tunneling microscopy (LT-STM) data reveal the surface structure as the CuPc coverage is stepwise increased. A highly ordered mixed phase as well as a disordered mixed phase can be found, where the highly ordered mixed phase seems to be thermodynamically favored. Low energy electron diffraction (LEED) measurements aid the STM analysis. Tentative models for the formation of the highly ordered mixed phase are given.