Unidirectionally Crystallized Stable n‐Type Organic Thin‐Film Transistors Based on Solution‐Processable Donor–Acceptor Compounds

Thin‐film formation by solution‐shearing technique is examined for layered‐crystalline donor–acceptor charge‐transfer compounds composed of 2,7‐dioctyl[1]benzothieno[3,2‐ b ][1]benzothiophene as a donor and optionally fluorinated derivatives of tetracyanoquinodimethane ( n = 0, 2, 4) as acceptors. Polycrystalline thin films of the compounds whose crystalline size is over 2 mm along the blade‐scan axis are successfully fabricated, and the formed films demonstrate anisotropic alignment of the crystalline grains where the crystal a ‐axis with the largest transfer integral is parallel to the blade‐scan axis. Such anisotropic alignment of large crystalline grains affords air‐stable n‐type field‐effect operation with a mobility as high as 0.61 cm 2 V −1 s −1 which is comparable to that of the single‐crystal devices.