| Autor: |
Crockett BM; Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon , Eugene, Oregon 97403-1253, United States., Jansons AW; Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon , Eugene, Oregon 97403-1253, United States., Koskela KM; Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon , Eugene, Oregon 97403-1253, United States., Johnson DW; Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon , Eugene, Oregon 97403-1253, United States., Hutchison JE; Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon , Eugene, Oregon 97403-1253, United States. |
| Abstrakt: |
Doped metal oxide nanocrystals that exhibit tunable localized surface plasmon resonances (LSPRs) represent an intriguing class of nanomaterials that show promise for a variety of applications from spectroscopy to sensing. LSPRs arise in these materials through the introduction of aliovalent dopants and lattice oxygen vacancies. Tuning the LSPR shape and energy is generally accomplished through controlling the concentration or identity of dopants in a nanocrystal, but the lack of finer synthetic control leaves several fundamental questions unanswered regarding the effects of radial dopant placement, size, and nanocrystalline architecture on the LSPR energy and damping. Here, we present a layer-by-layer synthetic method for core/shell nanocrystals that permits exquisite and independent control over radial dopant placement, absolute dopant concentration, and nanocrystal size. Using Sn-doped In 2 O 3 (ITO) as a model LSPR system, we synthesized ITO/In 2 O 3 core/shell as well as In 2 O 3 /ITO core/shell nanocrystals with varying shell thickness, and investigated the resulting optical properties. We observed profound influence of radial dopant placement on the energy and linewidth of the LSPR response, noting (among other findings) that core-localized dopants produce the highest values for LSPR energies per dopant concentration, and display the lowest damping in comparison to nanocrystals with shell-localized or homogeneously distributed dopants. Inactive Sn dopants present on ITO nanocrystal surfaces are activated upon the addition of a subnanometer thick undoped In 2 O 3 shell. We show how LSPR energy can be tuned fully independent of dopant concentration, relying solely on core/shell architecture. Finally, the impacts of radial dopant placement on damping, independent of LSPR energy, are explored. |
