Templating Effect for Organic Heterostructure Film Growth: Perfluoropentacene on Diindenoperylene

We present a systematic study of templating effects in organic heterostructure growth, that is, where the growth behavior of the top layer is significantly influenced by the structural and morphological properties of the bottom layer. We prepared thin films of the donor material diindenoperylene (DIP) differing in crystal structure, grain size, and grain orientation on indium tin oxide (ITO). The acceptor material perfluoropentacene (PFP) was chosen to be evaporated on DIP to form the heterostructure. We employed X-ray reflectivity and gazing incidence X-ray diffraction as well as atomic force microscopy to investigate the heterostructures. The structure and morphology of the PFP layers depend on the properties of the DIP layer underneath. Two main effects were observed: PFP molecules in the top layer tend to adopt the orientation of the DIP molecules in the bottom layer and the crystalline quality of the PFP layer correlates with the crystalline quality of the DIP layer underneath in terms of the in-plane coherent crystal size.