skip to main content

DOE PAGESDOE PAGES

Title: Ensemble brightening and enhanced quantum yield in size-purified silicon nanocrystals

Here, we report on the quantum yield, photoluminescence (PL) lifetime and ensemble photoluminescent stability of highly monodisperse plasma-synthesized silicon nanocrystals (SiNCs) prepared though density-gradient ultracentrifugation in mixed organic solvents. Improved size uniformity leads to a reduction in PL line width and the emergence of entropic order in dry nanocrystal films. We find excellent agreement with the anticipated trends of quantum confinement in nanocrystalline silicon, with a solution quantum yield that is independent of nanocrystal size for the larger fractions but decreases dramatically with size for the smaller fractions. We also find a significant PL enhancement in films assembled from the fractions, and we use a combination of measurement, simulation and modeling to link this ‘brightening’ to a temporally enhanced quantum yield arising from SiNC interactions in ordered ensembles of monodisperse nanocrystals. Using an appropriate excitation scheme, we exploit this enhancement to achieve photostable emission.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. North Dakota State Univ., Fargo, ND (United States)
  2. Univ. of Minnesota, Minneapolis, MN (United States)
Publication Date:
OSTI Identifier:
1053187
Report Number(s):
DOE/GO/88160--46
Journal ID: ISSN 1936-0851
Grant/Contract Number:
FG36-08GO88160
Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 6; Journal Issue: 8; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society
Research Org:
North Dakota State Univ., Fargo, ND (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE nanocrystalline silicon; polydispersity; photoluminescent stability; quantum yield