Dual- Low-Voltage Solution Processed Organic Thin-Film Transistors With a Thick Polymer Dielectric Layer

Threshold voltage (V_th) control using different metal gates (aluminum and gold) was applied to realize dual-V_th low-voltage solution processed organic thin film transistors (OTFTs). In the devices, the low-operation voltage was realized based on a channel engineering approach instead of using large gate dielectric capacitance, therefore, a relatively thick and low-dielectric constant polymer dielectric layer can be used. The devices present a mobility about 1.0 cm²/(V·s), ON/OFF ratio of 10⁵ and small subthreshold swing of 100 mV/decade with the maximum processing temperature not exceeding 100 °C. It was found that, even with a 400-nm thick polymer dielectric layer, since possible charge trapping effects was effectively suppressed by the crosslinking processes, well controlled V_th was achieved. Both unipolar single-V_th and dual-V_th inverters were fabricated, clearly showing the influence of V_th on the circuit operation and improved performance with the dual-V_th OTFT technology.