High‐Speed Direct Laser Writing of Silver Nanostructures via Two‐Photon Reduction

Despite the widespread use of metallic nanostructures in several emerging applications, high‐throughput template‐free fabrication techniques that are capable of patterning arbitrarily complex nanostructures are lacking. Two‐photon reduction‐based direct laser writing is a promising technique due to its ability to fabricate geometrically intricate metallic structures with sub‐diffraction nanoscale features. Unfortunately, the extremely low writing speed of ≈10 μm s −1 makes this process impractical for large‐scale manufacturing. The operating speed is currently limited by a lack of photoresist materials that can operate under high‐speed writing conditions. Herein, a silver‐containing aqueous photoresist recipe is presented that increases the writing speed to 1 cm s −1 while maintaining the ability to fabricate sub‐diffraction silver nanowires as thin as 500 nm. In addition, the electrical conductivity of the printed silver is within one‐fifth that of bulk silver. Strikingly, it is demonstrated here that the conventional design rule of using surfactants to promote high‐quality printing is faulty under high‐speed conditions. Instead, surfactants limit the throughput and are eliminated to enable high‐speed writing. The 1000× throughput scale‐up presented here significantly improves our ability to transition nano‐enabled devices from research laboratories to real‐world adoption.