Reversible and irreversible trapping at room temperature in poly(thiophene) thin-film transistors

We measured the bias stress characteristics of poly(thiophene) semicrystalline thin-film transistors (TFTs) as a function stress times, gate voltages, and duty cycles. At room temperature, the bias stress has two components: a fast reversible component and a slow long-lived component. We hypothesize that the irreversible component is due to charge trapping in the disordered areas of the semiconductor film. At low duty cycle (< 2%), the fast bias stress component is reversed during the off-part of the cycle therefore the observed threshold voltage (V-T) shift is only caused by long-lived trapping. Long-lived trapping follows power-law kinetics with a time exponent approximately equal to 0.37. We use these findings to estimate the lifetime of TFTs used as switches in display backplanes. (c) American Institute of Physics.