"Strain-Induced Modification of Optical Selection Rules in Lanthanide-Based Upconverting Nanoparticles"

Michael D. Wisser: Maverick Chea, Yu Lin, Di M. Wu, Wendy L. Mao, Alberto Salleo, and Jennifer A. Dionne; Nano Lett., 02/03/15.

Additional Authors: Maverick Chea, Yu Lin, Di M. Wu, Wendy L. Mao, Alberto Salleo, and Jennifer A. Dionne

Abstract:

Abstract Image

NaYF4:Yb3+,Er3+ nanoparticle upconverters are hindered by low quantum efficiencies arising in large part from the parity-forbidden nature of their optical transitions and the nonoptimal spatial separations between lanthanide ions. Here, we use pressure-induced lattice distortion to systematically modify both parameters. Although hexagonal-phase nanoparticles exhibit a monotonic decrease in upconversion emission, cubic-phase particles experience a nearly 2-fold increase in efficiency. In-situ X-ray diffraction indicates that these emission changes require only a 1% reduction in lattice constant. Our work highlights the intricate relationship between upconversion efficiency and lattice geometry and provides a promising approach to modifying the quantum efficiency of any lanthanide upconverter.