Hydrogen-bonded dimers of mono-alkylated diketopyrrolopyrroles and their physical properties

Judicious utilization of hydrogen bonding in diketopyrrolopyrroles (DPPs) could allow smooth carrier transfer when applied to organic semiconducting materials. In this study, we determined the association constants of dimerization by hydrogen bonding for a mono-alkylated DPP in the solution state to obtain basic insights that could aid in the utilization of hydrogen bonding. The IR spectroscopy, thermal analysis, and X-ray diffractometry results demonstrate that the hydrogen-bonded dimer structure was preferentially formed in the solid state. Electron transporting properties was only observed in the DPP derivatives, forming the hydrogen-bonded dimer structure, indicating the formation of a film morphology suitable for carrier-transport pathway.