Efficient Carrier Multiplication in Colloidal Silicon Nanorods

Carl Jackson Stolle, Xiaotang Lu, Yixuan Yu, Richard D. Schaller, Brian A. Korgel

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Auger recombination lifetimes, absorption cross sections, and the quantum yields of carrier multiplication (CM), or multiexciton generation (MEG), were determined for solvent-dispersed silicon (Si) nanorods using transient absorption spectroscopy (TAS). Nanorods with an average diameter of 7.5 nm and aspect ratios of 6.1, 19.3, and 33.2 were examined. Colloidal Si nanocrystals of similar diameters were also studied for comparison. The nanocrystals and nanorods were passivated with organic ligands by hydrosilylation to prevent surface oxidation and limit the effects of surface trapping of photoexcited carriers. All samples used in the study exhibited relatively efficient photoluminescence. The Auger lifetimes increased with nanorod length, and the nanorods exhibited higher CM quantum yield and efficiency than the nanocrystals with a similar band gap energy Eg. Beyond a critical length, the CM quantum yield decreases. Nanorods with the aspect ratio of 19.3 had the highest CM quantum yield of 1.6 ± 0.2 at 2.9Eg, which corresponded to a multiexciton yield that was twice as high as observed for the spherical nanocrystals.

Original languageEnglish
Pages (from-to)5580-5586
Number of pages7
JournalNano letters
Volume17
Issue number9
DOIs
Publication statusPublished - Sep 13 2017

Keywords

  • Auger recombination
  • Carrier multiplication
  • multiple exciton generation
  • nanorods
  • quantum confinement
  • silicon nanocrystals

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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