An STM study of molecular exchange processes in organic thin film growth

Abstract

The growth of a fullerene derivative (PCBM) on top of a layer of a tetrathiafulvalene (TTF) derivative previously deposited on Au(111) has been studied by scanning tunneling microscopy (STM). The results show that the preferential interaction with the gold substrate induces the exchange of PCBM molecules with the exTTF monolayer, expelling exTTF molecules to the outer surface. This exchange process is forbidden when the thickness of the exTTF layer increases above the monolayer, and the larger surface energy of PCBM leads to the growth of 3D islands ; Our work was supported by the MICINN of Spain (FIS2010-18847, FIS2012-33011), Comunidad de Madrid (NanobiomagnetS2009/MAT-1726), CONSOLIDER-INGENIO on Molecular Nanoscience (CSD2007-00010) and European Union (SMALL PITN-GA- 2009-23884)