Researchers are exploring ways to enhance upconversion photoluminescence in various nanocrystals and nanostructures, including those doped with lanthanides such as Yb and Er. Studies are investigating the use of plasmonic enhancement to improve upconversion emissions, with some focusing on specific materials like NaYF4 and gold nanorods. The goal of this research appears to be the development of more effective upconversion probes for applications such as theranostics.