The effect of hydrogen bond interactions on the electronic nature of DPP-based organic semiconductors: implications on charge transport

Abstract

In this work, we show that hydrogen bond interactions, in addition to directing supramolecular order, can have an intriguing effect on the molecular and electronic properties of DPP derivatives, facilitating redox processes in the solid state. As a result, charge carrier formation can be enhanced in devices, contributing to the improvement of electrical performances of two exceptionally small molecular semiconductors based on a thiophene-capped diketopyrrolopyrrole (DPP) as the electroactive component and amide groups as hydrogen-bonding units. Two different topologies of the amide groups were explored, C-centered and N-centered (HDPPBA-C and HDPPBA-N, respectively), and the results were compared to the HDPPH molecule with no amide groups. Spectroelectrochemical experiments, in conjunction with vibrational spectroscopies and DFT calculations, demonstrate that hydrogen bond formation promotes modifications on the effective conjugation length of the studied semiconductors, which may facilitate the generation of free charge carriers in organic field effect transistors (OFETs). These results open a new strategy towards the simple design of organic semiconductors and control over their morphological and electrical properties by simple hydrogen bond formation.