Aryl-Ethenyl-Substituted Diketopyrrolopyrrole Semiconductors with trans Configuration and Ultraclose π-Plane Stacking Distance

We present a new class of diketopyrrolopyrrole (DPP) derivatives, which comprise the ethenylidene linker that connects the DPP unit to aryls, such as thiophene (TE-DPP), furan (FE-DPP), and cyanothiophene (CNTE-DPP), respectively. The introduction of ethenylidene linkers led to extended π-conjugation length and enhanced intramolecular charge transfer, giving rise to prominent red shift in the visible region of the spectrum, low-lying lowest unoccupied molecular orbital (LUMO) level, and the narrow band gap. The single-crystal X-ray diffraction analysis reveals that the resulting compounds exhibit planar configurations with close π–π distances of 3.17 Å. Furthermore, these compounds exhibit one-dimensional arrangement, which benefits from intramolecular and intermolecular hydrogen bonds, facilitating short contact between donor and acceptor segments. Organic field-effect transistor (OFET) measurements reveal that TE-DPP and FE-DPP exhibit p-type transport behavior with maximum mobility of 0.05 and 0.18 cm2 V–1 s–1, respectively. While CNTE-DPP exhibits ambipolar transport characteristics with electron and hole mobilities up to 0.13 and 0.24 cm2 V–1 s–1, respectively. Our work demonstrates the potential of aryl-ethenyl-substituted diketopyrrolopyrroles (ArE-DPPs) as promising semiconducting materials for applications in organic electronic devices.