Nucleation and growth of thin films of rod-like conjugated molecules

Thin films formed from small molecules are rapidly gaining importance in different technological fields. To explain their growth, methods developed for zero-dimensional atoms as the film-forming particles are applied. However, in organic thin-film growth the dimensionality of the building blocks comes into play. Using the special case of the model molecule para-Sexiphenyl, we will emphasize the challenges that arise from the anisotropic and one-dimensional nature of building blocks. Differences or common features with other rod-like molecules will be discussed. The typical morphologies encountered for this group of molecules and the relevant growth modes will be investigated. Special attention is given to the transition between a flat-lying and upright orientation of the building blocks during nucleation. We will further discuss methods to control the molecular orientation and describe the involved diffusion processes qualitatively and quantitatively.