title: Plasmon-enhanced upconversion luminescence in single nanophosphor-nanorod heterodimers formed through template-assisted self-assembly.
abstract: We demonstrate plasmonic enhancement of upconversion luminescence in individual nanocrystal heterodimers formed by template-assisted self-assembly. Lithographically defined, shape-selective templates were used to deterministically coassemble single Au nanorods in proximity to single hexagonal (β-phase) NaYF4:Yb(3+),Er(3+) upconversion nanophosphors. By tailoring the dimensions of the rods to spectrally tune their longitudinal surface plasmon resonance to match the 977 nm excitation wavelength of the phosphors and by spatially localizing the phosphors in the intense near-fields surrounding the rod tips, several-fold luminescence enhancements were achieved. The enhancement effects exhibited a strong dependence on the excitation light's polarization relative to the rod axis. In addition, greater enhancement was observed at lower excitation power densities due to the nonlinear behavior of the upconversion process. The template-based coassembly scheme utilized here for plasmonic coupling offers a versatile platform for improving our understanding of optical interactions among individual chemically prepared nanocrystal components.
authors.affiliation: Department of Materials Science and Engineering, ‡Department of Electrical and Systems Engineering, §Department of Chemistry, ∥Department of Physics and Astronomy, and ⊥Department of Bioengineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Greybush
authors.forename: Marjan
authors.initials: M
authors.lastname: Saboktakin
authors.forename: Xingchen
authors.initials: X
authors.lastname: Ye
authors.forename: Cristian
authors.initials: C
authors.lastname: Della Giovampaola
authors.forename: Soong Ju
authors.initials: SJ
authors.lastname: Oh
authors.forename: Nathaniel E
authors.initials: NE
authors.lastname: Berry
authors.forename: Nader
authors.initials: N
authors.lastname: Engheta
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Murray
authors.forename: Cherie R
authors.initials: CR
authors.lastname: Kagan
mesh_terms: D019281:Dimerization; D006046:Gold / Q000737:chemistry; D049449:Luminescence; D008163:Luminescent Measurements; D053758:Nanoparticles / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*
chemical_list: D006046:Gold
keywords: gold nanorod; plasmon-enhanced luminescence; polarization dependence; single particle; template-assisted self-assembly; upconversion nanocrystals