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 ∼70 min. The temperature dependence of the retention time revealed a trapping mechanism with a trapping activation energy of ∼400 meV.