Emerging organic electronic device applications often require the structuring and processing of thin films at very different length scales.

Controlling the film morphology at the molecular level is essential for charge generation and electronic transport properties; structuring on the μm level is of interest for photonic effects; ultimately, the materials should be transferred defect-free and cheap into the final device.

For true large-scale applications in organic photovoltaics, we developed an ITO-free, flexible, transparent and conductive electrode made of a woven high-precision fabric, onto which solar cells can be deposited by roll-to-roll and printing high-throughput processes.

Turning to much smaller dimensions, we report on the development - and propose concepts for improvements - of simple sub-100 nm thick organic bilayer cyanine dye / C60 solar cells with good efficiencies. Cyanine dyes have found applications as photographic sensitizers, as fluorescent labels or in dye-sensitized solar cells.

We finally describe a liquid-liquid dewetting (LLD) process where the lateral size of cyanine dye / PCBM (a soluble C60-fullerene) phase structures can be controlled from 5 mm to well below 50 nm. Moreover, in this materials system, LLD induces a specific 2-dimensional arrangement (aggregates) of cyanine dye molecules on PCBM surfaces, most impressively demonstrated by enormous changes in the dye absorption characteristics.

The combination of length scale control in the phase structure with the initiation of dye aggregation gives LLD a unique attribute, with potential applications of such structured films ranging from organic solar cells to photonic structures.