Improved Performance of Fluorinated Copper Phthalocyanine Thin Film Transistors Using Para-hexaphenyl as the Inducing Layer

We demonstrate n-type organic thin film transistors (OTFTs) employing copper hexadecafluorophthalocyanine (CuPcF₁₆) as the active layer and para−hexaphenyl (p−6p) as the inducing layer. Compared with the CuPcF₁₆−based OTFTs without the p−6p inducing layer, the performance of the CuPcF₁₆/p−6p OTFTs is greatly improved. The charge carrier field-effect mobility μ, on−off current ratio I_on/I_off and threshold voltage V_T of the CuPcF₁₆/p−6p OTFTs are 0.07 cm²/V⋅s, 1.61×10⁵ and 6.28 V, respectively, approaching the level of a single crystal device. The improved performance is attributed to the introduction of p−6p to form a highly oriented and continuous film of CuPcF₁₆ with the molecular π–π stack direction parallel to the substrate.