Printing of Fine Metal Electrodes for Organic Thin‐Film Transistors

Abstract

Attributed to the excellent mechanical flexibility and compatibility with low-cost and high-throughput printing processes, the organic thin-film transistor (OTFT) is a promising technology of choice for a wide range of flexible and large-area electronics applications. Among various printing techniques, the drop-on-demand inkjet printing is one of the most versatile ones to form patterned electrodes with the advantages of mask-less patterning, non-contact, low cost, and scalability to large-area manufacturing. However, the limited positional accuracy of the inkjet printer system and the spreading of the ink droplets on the substrate surface, which is influenced by both the ink properties and the substrate surface energy, make it difficult to obtain fine-line morphologies and define the exact channel length as required, especially for relatively narrow-line and short-channel patterns. This chapter introduces the printing of uniform fine silver electrodes and down scaling of the channel length by controlling ink wetting on polymer substrate. All-solution-processed/printable OTFTs with short channels (<20 µm) are also demonstrated by incorporating fine inkjet-printed silver electrodes into a low-voltage (<3 V) OTFT architecture. This work would provide a commercially competitive manufacturing approach to developing printable low-voltage OTFTs for low-power electronics applications.