Fabricating organic transistors based on domain-ordered copper phthalocyanine film grown on oligothiophene epitaxial substrate

Organic field‐effect transistors were fabricated using a domain‐ordered copper phthalocyanine (CuPc) thin film as the active layer prepared by weak epitaxial growth (WEG) technology. CuPc was deposited onto α‐sexithiophene (α‐6T) and α,ω‐dihexylsexithiophene (α,ω‐DH6T) films acting as the epitaxial substrate to realize the domain‐order growth. As a result, the thin‐film morphology of CuPc exhibits many re‐ gional domain‐ordered structures measured by atomic force microscopy and X‐ray diffraction. The field‐effect mobilities are 0.11 and 0.085 cm2/Vs for the devices with CuPc/α‐6T and CuPc/α,ω‐DH6T, respectively. The threshold voltages were –7 V and –13 V for CuPc/α‐6T and CuPc/α,ω‐DH6T, respectively. The improved device performance could be attributed to the domain‐order structure of the CuPc thin film. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) A copper phthalocyanine (CuPc) thin film was prepared by introducing oligothiophene as the buffer layer. Domain‐order structure is then clearly observed that significantly depends on the thickness of oligothiophene. The corresponding field‐effect mobility of organic transistors is five times larger than that of devices based on single‐layer CuPc.