High-gain and low-hysteresis properties of organic inverters with an UV-photo patternable gate dielectrics

Low-hysteresis properties for an organic thin-film transistor (OTFTs) and a high-gain inverter were fabricated using a self-synthesized UV-photo patternable gate dielectric. The hysteresis behavior was not observed in the transfer characteristics of OTFTs or in the voltage transfer characteristics of the organic inverter. For a given dielectric thickness and applied voltage, pentacene OTFTs with inverter circuits were characterized by the field effect mobility, the on/off current ratio, threshold voltage (Vth), and the gain. The field effect mobility, Vth and the on/off currents ratio were 0.03 cm2/Vs,− 3.3 V and 106, respectively. The inverter has very large gain of 32 and matching input and output levels, despite having a positive switch-on voltage and slight hysteresis. From OTFT device and inverter circuit measurements, it was found that the hysteresis behavior was caused by the interface-state charge trapping between the gate dielectric and the pentacene semiconductor layer.