CONTROLLING PHOTON UPCONVERSION IN LANTHANIDE-DOPED NANOCRYSTALS FOR VARIOUS APPLICATIONS

Abstract

Lanthanide-doped upconversion nanoparticles (UCNPs) have drawn remarkable attention owing to their extraordinary optical properties and potential applications to energy harvesting, bio-imaging and optical cryptography. In this dissertation, we focused on controlling the optical properties of Ln-doped. We first developed a novel strategy to electrically modulate the upconversion luminescence based on the combination of UCNPs and electrochemically responsive organic molecules, paving the way towards dynamic pixels for multi-color displays and new non-linear optoelectronic nanodevices. Next, a simple and novel strategy was developed to greatly boost and direct the photon upconversion emission, resulting in 4 orders of magnitude brighter and >166 times faster spontaneous emission from gap-mode plasmon coupled UCNPs, accompanied by high quantum efficiency and directionality. Finally, a general and flexible strategy was developed to assemble randomly dispersed UCNPs into large-area compact aggregates with desired patterns, offering opportunities for applications such as anti-counterfeiting label and optical memory.