Low-voltage organic strain sensor on plastic using polymer/high- K inorganic hybrid gate dielectrics

Abstract

In this paper, gate-induced pentacene semiconductor strain sensors based on hybrid-gate dielectrics using poly-vinylphenol (PVP) and high-K inorganic, Ta₂O₅ are fabricated on flexible substrates, polyethylene naphthalate (PEN). The Ta₂O₅ gate dielectric layer is combined with a thin PVP layer to obtain very smooth and hydrophobic surfaces which improve the molecular structures of pentacene films. The PVP-Ta₂O₅ hybrid-gate dielectric films exhibit a high dielectric capacitance and low leakage current. The sensors adopting thin film transistor (TFT)-like structures show a significantly reduced operating voltage (~6V), and good device characteristics with a field-effect mobility of 1.89 cm²/V•s, a threshold voltage of -0.5 V, and an on/off ratio of 10³. The strain sensor, one of the practical applications in large-area organic electronics, was characterized with different bending radii of 50, 40, 30, and 20 mm. The sensor output signals were significantly improved with low-operating voltages.