Three-Terminal Floating-Gate Cell for Threshold-Voltage Control of Organic Thin-Film Transistors

Abstract

A floating-gate (FG) cell as a circuit-level approach to control the threshold voltage of organic thin-film transistors (TFTs) operated in the transdiode configuration is presented. Charging and discharging of the FG are achieved by controlling the charge leakage through the gate dielectric of one of the organic TFTs that constitute the FG cell. Using programming voltages not exceeding 4 V, systematic tuning of the threshold voltage to values between −0.5 and 2.6 V was achieved. The versatility of the concept is demonstrated by employing organic-TFT-based FG cells as transdiodes with programmable threshold voltage in passive rectifiers and diode-load inverters fabricated on flexible, transparent plastic substrates. Rectifiers with programmable FG cells show flatter frequency response, improved 3-dB point, and reduced ripple compared to conventional rectifiers. Inverters with programmable FG-transdiode load have larger small-signal gain, larger output-voltage swing, and larger noise margins than conventional diode-load inverters.