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Title: Efficient Carrier Multiplication in Colloidal Silicon Nanorods

Journal Article · · Nano Letters
 [1];  [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Texas, Austin, TX (United States). McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology
  2. Northwestern Univ., Evanston, IL (United States). Department of Chemistry; Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials

In this study, 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. Finally, 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.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Welch Foundation; National Science Foundation (NSF)
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1414421
Journal Information:
Nano Letters, Journal Name: Nano Letters Journal Issue: 9 Vol. 17; ISSN 1530-6984
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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