Strain Sensitivity and Transport Properties in Organic Field-Effect Transistors

We present the electromechanical characterization of organic field-effect transistors (OFETs) fabricated with different organic semiconductors. Pentacene- and poly(3-hexylthiophene-2,5-diyl) (P3HT)-based OFETs have been investigated as strain sensors, and a clear correlation between the structural and morphological properties of the active layer with the device sensitivity has been observed. The highly disordered structure of polymeric films, as P3HT, confirmed by morphological and structural investigations, gives rise to a dramatic reduction of the device response to mechanical stimuli. Nevertheless, an unambiguous, fast, and reproducible response has been obtained also for this material, which, being solution processible, represents a valuable solution for the fabrication of low-cost pressure sensors for a variety of innovative applications.