Film thickness dependency of the emission colors of PPE–PPVs in inkjet printed libraries

The influence on the emission color of π-conjugated polymers varying side chains, film thicknesses and thermal treatment were investigated in a parallel fashion. The respective thickness libraries of six alkoxy-substituted poly(p-phenyleneethynylene)-alt-poly(p-phenylenevinylene)s (PPE–PPVs) were prepared by inkjet printing in a controlled way. The optical properties of the printed libraries were screened utilizing high-throughput methods. It was found that the emission colors of the investigated polymers strongly depend on the inter-chain interactions which are increased with increasing film thickness and influenced by the side chains. Moreover, upon annealing at 70 °C, white emission was observed from the printed films.