Current-voltage hysteresis and memory effects in ambipolar organic thin film transistors based on a substituted oligothiophene

An ambipolar 5,5'-bis(fluoroalkyl) quarterthiophene exhibits memory effects in thin film transistors. The memory effect is based on hysteresis in the transfer (I-D-V-G) characteristics that is apparently due to charge trapping. Hysteresis induced by gate-bias stress was exploited to study nonvolatile floating gate memory effects. The ON state retention time for this memory device is similar to 70 min. The temperature dependence of the retention time revealed a trapping mechanism with a trapping activation energy of similar to 400 meV.