Polythiophene derivatives as chemical sensors: a DFT study on the influence of side groups

Conjugated polymers have been considered promising candidates for applications in chemical sensors, mainly due to their high versatility of synthesis, low cost, light weight, and suitable optoelectronic properties. In this context, polythiophene (PT) derivatives have been successfully employed. However, at the same time that the versatility of the synthesis allows the production of varied derivatives, the complexity of interactions with analytes hinders an efficient design of compounds with improved sensing properties. In the present report, electronic structure calculations were employed to identify promising PT derivatives for chemical sensor applications. Structural, optoelectronic, and reactivity properties of a set of branched PT derivatives were evaluated. Adsorption studies considering different gaseous compounds were conducted for selected systems. The results suggest that an appropriate choice of the side groups can lead to derivatives with improved sensorial properties. In particular, PT-CN derivative was identified as the most promising compound for high sensitive chemical sensors towards SO₂ and NH₃ analytes.