Roberto Faria1,Josiani Cristina Stefanelo1,João Henrique Rocha Matos1,José Alberto Giacometti1
São Carlos Institute of Physics, University of São Paulo1
In the last years, the organic electronics has attracted great efforts at fundamental and technological researches. The organic electronics enables large-area fabrication, the use of flexible substrates, solution processing at low temperatures, and deposition by printing techniques. Moreover, several technological devices, such as, flexible displays, disposable sensors, RFID tags and wearable electronics can be produced using organic materials. To make possible these applications, is needed the production of field-effect transistor, an essential circuit component, which is used to amplify and switch digital and analog signals. Due to its importance, there is great interest at fabrication of organic field-effect transistors (OFETs). Among the developed printing technologies, inkjet is one of the most appropriate for microelectronics. It is a noncontact technique which uses low amount of material to print defined patterns, avoiding waste; furthermore it enables to change the printed pattern with easiness. Here, we present OFETs fabricated at the bottom gate-top contact architecture with the semiconductor deposited by inkjet printing technique. The semiconductor used was the <i>6,13-bis(triisopropylsilylethynyl)-pentacene</i> (TIPS-pentacene), a promising material as p-type semiconductor, due to its high mobility, air stability and solution processability. In this work, the transistor performance was evaluated changing the distance between drops and printing patterns. The semiconductor was deposited on the organic dielectric layer. Different printing patterns of parallel lines were deposited with respect to direction of electronic conduction. Transistors presented higher performance for the pattern with same dispensing direction, achieving mobilities on the order of 10<sup>-2</sup> cm<sup>2</sup>/V.s and on/off ratio of 10<sup>4</sup>. Similar features were obtained for the distance between drops of 250 µm. The better OFETs performance is associated with the printed film morphology, due to homogeneous semiconductor layer and oriented crystallization on the direction electronic conduction.