Organic thin-film transistors with low threshold voltage variation on low-temperature substrates

We demonstrate a systematic approach to optimize pentacene-based thin-film transistors using a photolithographic-based process to integrate basic circuit components such as organic-based diodes, transistors, and capacitors to fabricate circuits such as inverters, ring oscillators, current mirrors, and rectifiers for radio-frequency identification and flexible display applications. Excellent threshold voltage control among transistors is demonstrated with a 2× reduction in threshold voltage (VT) standard deviation. Our integration methodology includes a seven-mask photolithography process that incorporates several discrete devices built with pentacene as the semiconductor and parylene as the gate dielectric and interlevel dielectric. In addition, the maximum temperature for all processes is 120°C.