Isomeric organic semiconductors containing fused-thiophene cores: Molecular packing and charge transport

Isomeric TF1 and TF2 with highly fused thiophene cores were designed and synthesized here, in which a highly planar molecular structure was obtained for TF1 with the face-to-face sulfur atoms in the lateral region and a twisted molecular backbone was observed for TF2 with the back-to-back sulfur atoms. It is worth noting that different intermolecular interactions dominated in TF1 and TF2 caused by their isomeric thiophene cores, in which strong π-π stacking was achieved for TF1, whereas sulphur-involved nonbonding intermolecular interactions dominated in TF2, leading to the different fluorescence behaviors and also the altered liquid crystalline phases. Finally, typical P-type charge transport behaviors were achieved in both TF1- and TF2-based solution-processed OFETs. Also owing to the much ordered molecular packing in TF1, a higher charge carrier mobility of 3.7 × 10^-3 cm² V^-1 s^-1 was achieved for TF1-based OFETs compared to TF2-based OFETs.