Bias stress induced threshold voltage instability in solution processed organic thin film transistor

Threshold voltage (V_th) instability of solution processed organic thin film transistors (TFTs) are investigated under different bias stress time and stress bias. Higher drain current (I_D) is observed during off-to-on sweep compare to the on-to-off sweep in the transfer characteristics. Negative gate bias stress results in a negative shift in the threshold voltage. This shift is attributed to the slow hole-trapping process and the relatively fast hole-detrapping process. The time dependence of threshold voltage is described by a carrier dynamic equation.