DFT study of the effect of fluorine atoms on the crystal structure and semiconducting properties of poly(arylene-ethynylene) derivatives.

The effect of fluorine substitution on the molecular structure, crystal packing, and n-type semiconducting properties of a set of poly(arylene-ethynylene) polymers based on alternating thiadiazole and phenyl units linked through ethynylene groups has been studied by means of Density Functional Theory. As a result, an enlargement in the interplanar distance between cofacial polymer chains, as well as a decrease of the electronic coupling and electron mobility is predicted. On the other hand, fluorination could facilitate electron injection into the material. A polymer containing both alkoxy pendant chains and fluorine atoms is proposed as a compromise solution between efficiency of electron injection and charge transport within the material.