A very colourful chemical process. There are several steps involved in producing this conductive plastic. The basic ingredients, which originate from the aromatic compounds thienothiophene and bithiophene, are the fundamental building blocks of many organic semiconductors. When these substances are mixed with the benign solvent N-butyl-2-pyrrolidone in the presence of a palladium catalyst, the solution almost immediately begins to change colour. The building blocks start assembling into polymer chains. These larger and longer molecules form the basis of the conductive plastic. Here, the solution has changed colour from yellow to deep red, before finally turning purple. The mixture is then washed using several different solvents to remove impurities. Finally, the solvents are removed using rotary evaporation – a method similar to distillation.
Photographer: Chalmers University of Technology | Henrik Sandsjö
