High-mobility Self-patterned Organic Thin-Film Transistors

O.D. Jurchescu
Wake Forest University, US

Keywords: organic semiuconductors, organic thin-film transistors

Summary:

The applications emerging from organic optoelectronics have broadened beyond those achievable with conventional silicon and are continuously expanding. Fabrication methods for such devices include roll-to-roll processing, inkjet printing and spray coating, which enable their manufacturing in large volumes and at low-cost. But their performance is challenged by complex film microstructure and deficient device operation, posing serious challenges to their incorporation in consumer applications. Several methods for controlling and optimizing device performance in solution-deposited organic thin-film transistor (OTFT) based on small-molecule organic semiconductors will be illustrated. Particular emphasis will be given to spray-coating, which allows fast deposition over large-areas with only a minimal compromise in device performance. OTFT patterning is achieved by exploiting film-forming properties on chemically modified surfaces. This results from control of the molecular orientation by tuning halogen-halogen interactions between the organic semiconductor and self-assembled monolayers (SAMs) present at the surface of source and drain electrodes. Consequently, the obtained on/off ratio and charge carrier mobility are as high as 10^7 and 1 cm2/Vs respectively, compared to 10^4 and 10^(-3) cm2/Vs in un-patterned devices. The ability to pattern OTFTs is critical for manufacturing high-performance devices, as it reduces the leakage currents, and promotes superior electrical performance.