High-performance air-stable n-type transistors with an asymmetrical device configuration based on organic single-crystalline submicrometer/nanometer ribbons

High-performance air-stable n-type field-effect transistors based on single-crystalline submicro- and nanometer ribbons of copper hexadecafluorophthalocyanine (F16CuPc) were studied by using a novel device configuration. These submicro- and nanometer ribbons were synthesized by a physical vapor transport technique and characterized by the powder X-ray diffraction pattern and selected area electron diffraction pattern of transmission electron microscopy. They were found to crystallize in a structure different from that of copper phthalocyanine. These single-crystalline submicro- and nanometer ribbons could be in situ grown along the surface of Si/SiO2 substrates during synthesis. The intimate contact between the crystal and the insulator surface generated by the in situ growing process was free from the general disadvantages of the handpicking process for the fabrication of organic single-crystal devices. High performance was observed in devices with an asymmetrical drain/source (Au/Ag) electrode configuration because in such devices a stepwise energy level between the electrodes and the lowest unoccupied molecular orbital of F16CuPc was built, which was beneficial to electron injection and transport. The field-effect mobility of such devices was calculated to be similar to 0.2 cm(2) V-1 s(-1) with the on/off ratio at similar to 6 x 10(4). The performances of the transistors were air stable and highly reproducible.