Absorption Properties of Metal-Semiconductor Hybrid Nanoparticles

Ehud Shaviv, Olaf Schubert, Marcelo Alves-Santos, Guido Goldoni, Rosa Di Felice, Fabrice Vallée, Natalia Del Fatti, Uri Banin, Carsten Sönnichsen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

190 Scopus citations

Abstract

The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

Original languageAmerican English
Pages (from-to)4712-4719
Number of pages8
JournalACS Nano
Volume5
Issue number6
DOIs
StatePublished - 28 Jun 2011

Keywords

  • DDA
  • Janus particles
  • absorption
  • exciton
  • hybrid nanoparticles
  • plasmon

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