Fluorinated copper-phthalocyanine-based n-type organic field-effect transistors with a polycarbonate gate insulator

Fluorinated copper-phthalocyanine (F16CuPc) thin films were prepared by using a vacuum evaporation technique and were applied to n-type organic field-effect transistors (OFETs) as active channel layers combined with a spin-coated polycarbonate thin-film gate insulator. The output characteristics of the resulting n-type OFET devices with bottom-gate/bottom-contact structures were investigated to evaluate the performances such as the field effect mobility (μFE), the on/off current ratio (Ion/off), and the threshold voltage (Vth). A relatively high field effect mobility of 6.0 x 10-3 cm2/Vs was obtained for the n-type semiconductor under atmospheric conditions with an on/off current ratio of 1 x 104 and a threshold voltage of 5 V. The electron mobility of the n-type semiconductor was found to depend strongly on the growth temperature of the F16CuPc thin films. X-ray diffraction profiles showed that the crystallinity and the orientation of the F16CuPc on a polycarbonate thin film were enhanced with increasing growth temperature. Atomic force microscopy studies revealed various surface morphologies of the active layer. The field effect mobility of the F16CuPc-OFET was closely related to the crystallinity and the orientation of the F16CuPc thin film.