We report on parasitic contact effects in organic thin film transistors (OTFTs) fabricated with pentacene films. The influence on the OTFT performance of the source and drain contact metal and the device design was investigated. Top contact (TC) and bottom contact (BC) gated transmission line model (gated-TLM) test structures were used to extract the combined parasitic contact resistance as a function of gate voltage swing and drain-source voltage for OTFTs with gold source and drain contacts. For comparison BC test structures with palladium contacts were studied. Differences in the bias dependence of the contact resistance for TC and BC OTFTs indicate that charge injection and device performance are strongly affected by the device design and processing. The results from this investigation show that TC and BC device performances may be contact limited for high mobility OTFTs with channel lengths less than 10μm.

We have fabricated pentacene organic thin-film transistor (OTFT) driven active matrix organic light-emitting diode (OLED) displays on flexible polyethylene terephthalete substrates. These displays have 48×48 bottom-emission OLED pixels with two pentacene OTFTs used per pixel. Parylene is used to isolate the OTFTs and OLEDs with good OTFT yield and uniformity.

We have fabricated organic thin-film transistor (OTFT)-driven active matrix liquid crystal displays on flexible polymeric substrates. These small displays have 16×16 pixel polymer-dispersed liquid crystal arrays addressed by pentacene active layer OTFTs. The displays were fabricated using a low-temperature process (<110 °C) on flexible polyethylene naphthalate film and are operated as reflective active matrix displays.

Analysis of carrier transport in quaterrylene thin film transistors formed by ultraslow vacuum deposition J. Appl. Phys.

We use grazing incidence x-ray scattering to study the molecular structure and morphology of thin ͑Ͻ70 ML͒ crystalline films of 3,4,9,10-perylenetetracarboxylic dianhydride ͑PTCDA͒ on Au͑111͒ surfaces as a function of film thickness, substrate temperature, and growth rate. Although the first two PTCDA monolayers grow in a layer-by-layer fashion, the film evolution beyond the second monolayer depends strongly upon the growth conditions resulting in low-temperature ͓i.e., nonequilibrium ͑NEQ͔͒ and high-temperature ͓equilibrium ͑EQ͔͒ growth regimes. In the NEQ regime, the films roughen monotonically with increasing film thickness, but retain a well-defined film thickness. Furthermore, we find that these films have a lattice strain which is independent of film thickness. In the EQ regime, the film acquires a three-dimensional morphology for thicknesses Ͼ2 ML, and the lattice strain decreases rapidly with increasing thickness. We also show that the transition between the NEQ and EQ regimes is sharp and depends upon the balance between the growth rate and substrate temperature. These results suggest that the PTCDA/Au͑111͒ system is thermodynamically described by incomplete wetting, and that strain and kinetics play an important role in determining molecular organic film characteristics.