A scalable fabrication method for gold nanodisk-upconverting nanoparticle hybrid nanostructures.

Plasmonic nanostructures can be used to enhance the efficiency of upconversion nanoparticles (UCNPs) and enable new functionalities. However, the fabrication of these hybrid plasmon-UCNP nanostructures has traditionally relied on either wet chemistry or nanolithography routes that are difficult to control, scale up, or both. In this work, we present a scalable nanofabrication process, capable of producing a massive array of gold-UCNP hybrid nanostructures over a few mm area and with excellent uniformity in the photoluminescence intensity. This new approach combines the scalability of the bottom-up self-assembly method and the precision of the top-down nanolithography approach. It provides an efficient alternative route for the production of plasmonically enhanced UCNPs. A detailed discussion on the optimization of the UCNP self-assembly, the gold nanodisk lithography, and the nanopattern transfer processes is presented here. Additionally, we showcase the potential of this new approach for fabricating mechanical force sensors based on the selective plasmonic enhancement of the UCNP emission. This new approach holds great potential in facilitating the production of plasmonically enhanced UCNPs that can be deployed for both imaging and sensing applications.