Architecting Layered Crystalline Organic Semiconductors Based on Unsymmetric π‑Extended Thienoacenes

Herein,
we demonstrate that engineered end-cap substitution for
unsymmetric extended π-cores effectively achieves well-ordered
two-dimensional (2D) molecular packing and thus realizes high-performance
organic semiconductors (OSCs). We developed phenyl- and decyl-substituted
benzothieno­[6,5-b]­benzothieno­[3,2-b]­thiophenes (BTBTTs) as solution-processable OSCs, providing layered
single-crystalline thin-film transistors with a hole mobility of up
to 12 cm2 V–1 s–1.
The compound formed a bilayer-type layered herringbone
packing in which the unsymmetric π-core aligned unidirectionally
to form the respective molecular layers, owing to the well-balanced
contributions of intermolecular interactions between the π-cores
and between the respective end substituents. The eventual close intralayer
molecular packing afforded a small effective mass and high thermal
stability. These findings will be crucial for expanding the ability
to develop high-performance OSCs.