Threshold voltage control in organic thin film transistors with dielectric layer modified by a genetically engineered polypeptide

This is the published version. Copyright 2010 American Institute of PhysicsPrecise control over the threshold voltage of pentacene-based organic thin film transistors was achieved by inserting a genetically engineered quartz-binding polypeptide at the semiconductor-dielectric interface. A 30 V range was accessed with the same peptide by adjusting the pH of the solution for peptide assembly while leaving other device properties unaffected. Mobility of 0.1–0.2 cm2 V−1 s−1 and on/off current ratio of >106 could be achieved for all devices regardless of the presence of the neutral peptide or the peptide assembled in acidic or basic conditions. This shift in threshold voltages is explained by the generation of charged species and dipoles due to variation in assembling conditions. Controlling device characteristics such as threshold voltage is essential for integration of transistors into electronic circuits

Solvent-Dispersed Benzothiadiazole-Tetrathiafulvalene Single-Crystal Nanowires and Their Application in Field-Effect Transistors

A new organic semiconductor (BT-TTF) based on molecular moieties of benzothiadiazole and tetrathiafulvalene was designed and synthesized, and its structure, molecular packing and charge-transporting properties were determined. Thermal properties, electrochemical behaviors, and optical absorption of this molecule were studied by using differential scanning calorimetry/thermal gravimetric analysis, cyclic voltammetry, and ultraviolet–visible spectroscopy, respectively. Its bulk and nanowire single crystals were prepared and characterized by X-ray crystallography, scanning electron microscopy, transmission electron microscopy, and field-effect transistors. It is found that short intermolecular S···S (3.41 Å), S···C (3.49 Å), and S···N (3.05 Å) contacts define the solid-state structure of BT-TTF single crystals which π-stack along the [100] with interplanar distances of 3.49 Å. Solvent-cast single-crystal nanowire transistors showed mobilities as large as 0.36 cm²/(V s) with current on/off ratios of 1 × 10⁶. This study further illustrates the impact of molecular design and a demonstration of high-performance single-crystal nanowire transistors from the resulting semiconductor