Understanding temperature dependence of threshold voltage in pentacene thin film transistors

Threshold voltage in the pentacene-based organic thin film transistors is found to be linearly increased with decreasing measuring temperature, indicating that the threshold voltage is dominated by the deep hole trapping in an approximately energy-independent trap distribution. The slope of threshold voltage vs temperature is greatly reduced at 200–210 K when temperature is decreased, corresponding to a reduction in the deep trap density. H2O confined in pentacene is considered as one of the sources of the deep hole traps, and the slope change in the temperature dependence of threshold voltage is attributed to the phase transition of supercooled H2O.