TY - JOUR
T1 - Efficient Carrier Multiplication in Colloidal Silicon Nanorods
AU - Stolle, Carl Jackson
AU - Lu, Xiaotang
AU - Yu, Yixuan
AU - Schaller, Richard D.
AU - Korgel, Brian A.
N1 - Funding Information:
Financial support of this work was provided by the Robert A. Welch Foundation (grant no. F-1464) and the National Science Foundation (grants no. CHE-1308813 and IIP-1134849). Financial support was also provided to C.J.S. by the National Science Foundation Graduate Research Fellowship Program under grant no. DGE-11100007. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, under contract no. DE-AC02-06CH11357.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/9/13
Y1 - 2017/9/13
N2 - 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.
AB - 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.
KW - Auger recombination
KW - Carrier multiplication
KW - multiple exciton generation
KW - nanorods
KW - quantum confinement
KW - silicon nanocrystals
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U2 - 10.1021/acs.nanolett.7b02386
DO - 10.1021/acs.nanolett.7b02386
M3 - Article
C2 - 28762274
AN - SCOPUS:85029397379
VL - 17
SP - 5580
EP - 5586
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 9
ER -