Direct Ink‐Jet Printing of Ag–Cu Nanoparticle and Ag‐Precursor Based Electrodes for OFET Applications

Abstract

The field of organic electronics has seen tremendous progress over the last years and all‐solution‐based processes are believed to be one of the key routes to ultra low‐cost roll‐to‐roll device and circuit fabrication. In this regard a variety of functional materials has been successfully designed for inkjet printing. While orthogonal‐solvent approaches have frequently been used to tackle the solubility issue in multilayer solution processing, the focus of this work lies on printed metal electrodes for organic field‐effect transistors (OFET) and their curing concepts. Two metallic inkjet‐printable materials are studied: i) a silver‐copper nanoparticle based dispersion and ii) a soluble organic silver‐precursor. Photoelectron spectroscopy reveals largely metallic properties of the cured materials, which are compared with respect to OFET performance and process‐related issues. Contact resistance of the prepared metal electrodes is significantly larger than that of evaporated top‐contact gold electrodes. As direct patterning via inkjet printing limits the reliably achievable channel length to values well above 10 μm, the influence of contact resistance is rather small, however, and overall device performance is comparable.

Metal-based Inkjet Inks for Printed Electronics

“…Applied to printed electronics, inkjet printing enables patterning with high resolution: line and space dimensions can be as small as 10-20 μm, that is at least five times better than the current resolution of screen printing [13,14].…”

Sintering Behavior of Copper Nanoparticles

“…10,11 However, their price hinders their commercialization. Therefore, the development of a low-cost printing material that can replace silver for the printing of conducting patterns is important for the advancement of printed electronics.…”

Electro-Mechanical Testing of Conductive Materials Used in Flexible Electronics

“…Metal and ceramic films are being deposited onto polymer substrates not only using traditional deposition methods but also with advanced roll-to-roll (Ahn and Guo, 2008;Dupont et al, 2012) and inkjet printing (Forrest, 2004;Gamerith et al, 2007) techniques. Due to the large differences in the elastic moduli of the ceramics, metals, and polymers used to fabricate flexible devices, large strains (>10% and even up to 100%) can be achieved with proper device design (Wagner and Bauer, 2012).…”