Sequence and assembly of conjugated polymer by high-resolution imaging

In this talk I will demonstrate that high resolution scanning tunnelling microscopy (STM) is capable of delivering crucial information — that cannot be achieved by any other current analytical method — about “real world” electronic and energy materials. In particular, I will show that by combining vacuum electrospray deposition (ESD) and high-resolution STM, it is possible to image conjugated polymers used in organic electronics and photovoltaic devices with unprecedented details. Based on this, it becomes possible to sequence the polymers by visual inspection and to determine their molecular mass distribution by simply counting the repeat units. Moreover, I will demonstrate that we can precisely determine the nature, locate the position, and ascertain the number of synthetic defects in the polymer backbone.1-2 The analysis of our high- resolution images univocally demonstrates that one of the main drivers for backbone conformation and polymer self-assembly is the maximization of alkyl side-chain interdigitation. On this basis, we investigate the 2D assembly of a series of conjugated polymers with the aim of gaining insight in the molecular microstructure of the corresponding 3D functional thin films.4,5