Organic inverter using two transistors with different channel thicknesses

We report on p-channel depletion mode organic inverter composed of two pentacene thin-film transistors (TFTs), which have different channel thickness each other. Adopting thin hydrophilic AlOx as dielectric, the 25 nm-thin channel pentacene TFT showed lower threshold voltage (VTH) than that of 50 nm-thick channel-TFT, while on hydrophobic poly-4-vinyphenol (PVP) dielectric the results became opposite. We utilized the different VTH caused by different channel thickness to operate the inverter that consists of driver- and load-TFTs. The 50 nm-thick pentacene operated as the channel layer of driver-TFT on AlOx, but on PVP dielectric the 25 nm-thin pentacene layer played as the driver channel. Maximum voltage gain of ∼22 under −8 V supply voltage was achieved when the dielectric layer was optimized.