Inkjet printed organic transistors for sustainable electronics

Embedded paper electronics is a promising solution for the future of electronics, and thus the goal for this paper is to show the pathway toward achieving inkjet solutions for the realization of complex circuitry on the cheapest synthetic material made by humankind: PAPER. A direct write technology, inkjet printing transfers the designed pattern directly to the substrate. Inkjet technologies have gained a lot of ground as a more accurate and economic fabrication method than traditional lithography. The challenge of this work is to identify the right materials and to show the printability of all the building blocks of an organic field-effect transistor (OTFT). For the semiconductor, a highly soluble pentacene precursor, 13,6-N-Sulfinylacetamidopentacene, is proposed. Anisole, a high boiling point solvent is chosen to insure proper jetting of the solution. The solution jets well and it has to be used right after preparation as its printability degrades with time. For the gate dielectric, two solutions are proposed: (i) using the paper itself as an insulator and print a bottom gate device on both sides of a double sided glossy paper, (ii) a pentacene impurity, of 6,13-pentacenequinone (PQ), in a top gate configuration, which may improve the device mobility by reducing the scattering sites at the semiconductor-dielectric interface. For the electrodes, a printable nano-particle based silver ink has to be modified to match the work function with pentacene, or replaced with an alternate printable material like Carbon Nanotubes (CNTs). Preliminary electrical testing of the pentacene film printed directly on paper shows good conduction properties for a 25 µm channel length. Further improvement of the pentacene film performance is proposed. This work establishes the foundation for the first fully printed OTFT on paper.