Review on dry film photoresist-based patterning of Ag nanowire flexible electrodes for wearable electronics

Silver (Ag) nanowires have attracted significant attention as flexible electrodes for various wearable electronic devices owing to their excellent optical and electrical properties. Patterning is an important step in the fabrication of Ag nanowire electrodes of appropriate size and shape for electronic device applications. Among the various methods to pattern Ag nanowires, photolithography using a liquid photoresist is the most widely used. However, some factors have limited an extensive use of this method, such as the non-uniform thickness of liquid photoresist on large-scale coatings and the requirement of a post-annealing step that limits the application to few polymeric substrates. In turn, these factors affect the successful application of the roll-to-roll fabrication process. Dry film photoresist (DFR), a solid-state film-type photoresist, can enable a fast and simple patterning process at lower temperatures, as DFR-based patterning process only requires a simple lamination step to coat the photoresist on the substrates. The DFR process is performed at a temperature below 80 °C, which enables the application of most polymeric substrates. Furthermore, this process doesn’t involve any additional post-annealing process, which makes it an appropriate technology for the roll-to-roll fabrication process. Owing to the advantages of DFR patterning, several recent studies have focused on this process for Ag nanowires patterning. This review provides an overview of successful examples of Ag nanowire patterning based on the use of DFR, along with the application of patterned Ag nanowires substrates as obtained by this method.