Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm2 V–1 s–1 (with a maximum mobility of 2.48 cm2 V–1 s–1), was obtained from solution-processed thin-film transistors, one of the highest mobilities reported to date. In contrast, the reference polymer with a branched alkyl side chain gave an average hole mobility of 0.30 cm2 V–1 s–1 and a maximum mobility of 0.57 cm2 V–1 s–1. This is largely explained by the polymer packing: our new polymer exhibited a π–π stacking distance of 3.58 Å, while the reference polymer showed a distance of 3.76 Å.