Cyano-position engineering in thiophene-DPP small molecules enables efficient N-type charge transport.

Vinylene-bridged thiophene-DPP molecules with cyano substituents at varied positions reveal strong positional effects. Only 3-CN-DOPPD exhibits efficient n-type transport with μe up to 0.15 cm2 V-1 s-1, enabled by its deeper LUMO, larger dipole, and favorable herringbone-like packing.