Functional landscaping of molecular films on oxides


funCOS showcase

With funCOS we propose an interdisciplinary coordinated research program which will aim at providing the urgently required fundamental understanding in the emerging field of organic films on oxides. Our strategy is based on a unique combination of competences at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in the fields of organic molecular films and of oxide surfaces and nanostructures.

The first phase of the project concentrates on simple molecular films on simple oxides. The fundamental knowledge gained will lead to the second phase of the project where complex films on nanostructured oxide surfaces are studied. Finally, we will also address oxide nanostructures and structure–property relationships.

In order to obtain maximum coherence within this collaborative research project, three prototype oxides: MgO, cobalt oxides (CoO, Co3O4), and TiO2 were selected and the target molecules are the important class of tetrapyrrole derivatives. The funCOS Showcase Systems propose specific examples from these toolboxes.

Phase 1: Controlled growth of uniform organic films on uniform oxide surfaces

Phase 1: From uncontrolled to controlled growth The aim of Phase 1 is the growth of uniform molecular films of organic molecules on simple oxide surfaces. The primary goal of funCOS is to develop a general knowledge-driven approach. To this end, the detailed understanding of the bonding sites, the bonding mechanisms and energetics, and the kinetics of structure formation is paramount. From these fundamental insights, the common principles that control the growth and the properties of organic molecules on oxide surfaces will emerge. To exemplify the new concepts underlying funCOS, we plan to demonstrate how the growth mode of an organic molecular film on an ordered oxide surface can be switched from a disordered three-dimensional growth to a two-dimensional growth with well-defined molecular orientation, and short- and long-range order.

Phase 2: Nanostructured organic films on nanostructured oxide surfaces

Phase 2: Complex nanostructured surfaces The aim Phase 2 is the controlled formation of nanostructured films. The general principles that govern selectivity in molecule–oxide interaction must be explored. Here, funCOS strategy involves patterned oxide surfaces and the use of linker units on the organic molecules. Dimensionality and size of the structural areas will be varied from the nano to the micrometer range. Our goal is the preparation of a two-dimensional nanostructured film with atomically well-defined anchoring sites, molecular orientation, and order.

Phase 3: Nanostructures, structure-property relationships, and routes for utilization

The funCOS vision Finally, a subset of molecule–oxide systems will be chosen based on the results of Phase 1 and Phase 2, and based on potential relevance for application, e.g. in the fields of molecular electronics, solar energy conversion, sensors, or catalysis. These systems may preferentially come from the funCOS toolboxes, but this part is explicitly open to other molecule–oxide systems as well. The idea is that the conceptual understanding generated by funCOS has a general impact for functional organic layers on oxide surfaces. Oxide nanostructures, a field where some funCOS partners provide exceptional expertise, will start to play an essential role in this project phase. Moreover, we will focus on the transfer of funCOS research from ideal UHV to realistic growth and operating conditions: How can the new concepts and building principles be transferred from ideal to realistic conditions?

It is our vision that, at this point, knowledge-based functional landscaping of real oxide surfaces will become a realistic strategy for the design of novel hybrid materials.