Enhancing Charge Transport in Supramolecular Semiconductors by Strategic Hydrogen-Bonding Positioning

Hydrogen-bonded semiconductors stand among the next generation of electronic materials thanks to their promising and versatile properties. Hydrogen-bonding has been proven to effectively compete with traditional p-p stacking, yielding well-connected structures that enhance device morphology and electrical performance. Nevertheless, the precise positioning of hydrogen-bonding units within the molecular structure of p-conjugated segments, can significantly shape the supramolecular architectures that dictate the pathways for charge carriers and ultimately, device efficiency. We elucidate this scenario by exploring diketopyrrolopyrrole (DPP) molecules featuring amide units strategically positioned at varying distances from the DPP core. Using a comprehensive combination of spectroscopy, structural and microscopy tools, we rationalize the charge transport properties through a contactless technique. Our results reveal that the proximity of the amide units to the DPP core governs the suppression or promotion of intermolecular hydrogen-bonding, resulting in materials exhibiting distinct crystalline or amorphous structures, along with divergent values of photoconductivity and charge carrier lifetimes. More importantly, the strategic positioning of hydrogen-bonding units represents the next step towards integrating hydrogen-bonded small molecules into practical optoelectronic devices