Alexander Friedrich Knobloch

Printed polymer transistors

Integrated plastic circuits (IPCs) based on organic field-effect transistors (OFETs) have many advantages. One potential is the use for commercial applications such as low cost ident-tags or electronic barcodes. In order to achieve low production cost, the transistors must be prepared by printing processes. In this paper, we present OFETs and organic inverters based on functional polymers with single layers applied by pad and screen printing. The pad printing technique is an efficient method for patterning the electrodes of an OFET. With this technique, dimensions of 20 /spl mu/m were reached. Source-drain and gate electrodes consisting of either polyaniline, carbon black conductive ink, gold, or silver filled ink were printed. With these structures, OFETs were assembled, in which poly(3-alkylthiophene) served as the semiconductor, and poly(4-hydroxystyrene) as the insulator. These polymers were deposited homogeneously by screen printing or spin coating. In addition, a gate dielectric for an OFET was also pad printed. A full organic inverter with all electrodes printed is introduced. As the production speed of the presented printing techniques has the ability to be scaled up, the potential for high volume printing of organic electronics is proven.

Applicability of coating techniques for the production of organic field effect transistors

Polymer electronics circuits based on organic field effect transistors (OFETs) have the prospect of becoming low cost products. This relies mainly on the fact that the polymers are solution processable and thus can be treated with printing and coating techniques. We investigate the applicability of different coating techniques for those layers in the OFET which do not necessarily need to be patterned, i.e. the semiconductor and dielectric insulator. The results are given in respect of layer quality and transistor operation. The investigated methods are doctor blading and screen printing which have the potential for roll-to-roll processing. Both methods are compared to spin coating, which is well established but restricted to batch processing.