Tuning Charge Transport in Organic Semiconductors via Backbone-Remote Hydrogen Bonding and Fluorination

The interplay of noncovalent interactions is a powerful tool for enhancing charge transport and device morphology in organic electronic systems. Organic semiconductors, characterized by aromatic rings, primarily rely on π-π stacking to form supramolecular structures. However, introducing additional noncovalent interactions, offers alternative routes for tuning aggregation and improving optoelectronic properties. Recently, backbone fluorination has become a powerful molecular design strategy to simultaneously boost charge transport and control the morphology of organic electronic devices. Here we explore the charge transport properties of a series of hydrogen-bonded quinquethiophene-rhodanine semiconductors featuring different fluorinated substituents that are remotely located from the conjugated backbone. By combining optical and vibrational spectroscopy, electrochemistry, microscopy and contactless microwave conductivity techniques, we establish clear correlations between the fluorination degree, supramolecular organization, and charge carrier dynamics. We demonstrate through this molecular design that even though the fluorinated moieties are not incorporated into the conjugated backbone or in the solubilizing alkyl tails, they play an essential role in the final charge transport properties. More importantly, our results provide general design guidelines for fluorinated 2 supramolecular semiconductors, and highlight fluorination in combination with H-bonding as an effective strategy for controlling multiscale structure-property relationships in organic electronic materials.