Solvent-Free Printing of Flexible Organic Thin Film Transistors by Ultrasonic Welding

A novel fabrication technique for making plastic electronics has been developed by applying an ultrasonic welding method that is already widely used in cutting, molding, and joining plastic sheets and parts for many industrial products. One major use of ultrasonic welding is the assembly of blood transfusion bags and other medical supplies, because the inert plastic parts can be joined and sealed without any adhesive agent and within a very short processing time. In this study, the same method is applied to make plastic electronics. The successful fabrication of organic TFTs is shown without affecting the gate insulator layer and the self-assembled monolayer (SAM) of pentafluorobenzenethiol (PFBT). We therefore demonstrate that ultrasonic welding can also be used to fabricate plastic electronics. Using this process, for example, one could add electronic functionality not only on the surface of a blood transfusion bag, but also in or through the welding margin at the fringe of the bag.