Hysteresis mechanism in low-voltage and high mobility pentacene thin-film transistors with polyvinyl alcohol dielectric

In this letter, the hysteresis mechanism of organic thin-film transistors (OTFTs) with polyvinyl alcohol (PVA) as gate dielectric is studied. By examining OTFTs with a blocking polymer layer between gate and PVA or between channel and PVA, we confirm that the origin of the hysteresis is caused by the holes injected from the gate and/or from the channel and trapped in the interface of pentacene/PVA and the PVA bulk. A method is proposed to reduce the hysteresis. As a result, a pentacene OTFT with free-hysteresis and high mobility of 1.8 cm2/Vs is achieved by a triple-layer polymer dielectric at low-operating voltages.