Field-effect transistors using Langmuir-Blodgett films of neutral long-chain TCNQ derivatives

Fabrication of field-effect transistors (FET) using the Langmuir-Blodgett films of neutral TCNQ derivatives with long alkyl-chain is reported. The films of neutral TCNQ derivatives (Cn-TCNQ; n = 12, 15, 18) were employed as the active layers of FET. The FET characteristics of n-type semiconductor were clearly observed. It was found that the field-effect mobility depends on the alkyl-chain length. Infrared absorption spectroscopy implies that the lateral packing manner of molecules is affected by whether the number of carbon atoms in the alkyl-chain is odd or even. Such odd-even effect seems to be responsible for the different field-effect mobility values.