Organic thin film phototransistors and fast circuits

We have fabricated organic thin film transistors (OTFTs) using the small-molecule organic semiconductor naphthacene as the active layer material with field-effect mobility greater than 0.1 cm/sup 2//V-s. This mobility is acceptable for several large-area electronic applications. OTFTs fabricated using naphthacene films show a large photosensitivity, of potential interest for applications requiring phototransistors. The threshold voltage and subthreshold region electrical characteristics of naphthacene OTFTs allow the fabrication of OTFT circuits without active layer patterning and do not require the use of a level shift stage such as that used to fabricate pentacene OTFT circuits. 5-stage ring oscillators fabricated with naphthacene OTFTs have single-stage propagation delay of less than 28 /spl mu/s; the fastest organic circuits reported to date.