Campus Units
Chemistry, Ames Laboratory
Document Type
Article
Publication Version
Published Version
Publication Date
12-23-2011
Journal or Book Title
Journal of Physical Chemistry C
Volume
116
Issue
4
First Page
2791
Last Page
2800
DOI
10.1021/jp210949v
Abstract
Thick-shell CdSe/nCdS (n >10) nanocrystals were recently reported that show remarkably suppressed fluorescence intermittency or "blinking" at the single-particle level as well as slow rates of Auger decay. Unfortunately, whereas CdSe/nCdS nanocrystal synthesis is well-developed up to n < 6 CdS monolayers (MLs), reproducible syntheses for n > 10 MLs are less understood. Known procedures sometimes result in homogeneous CdS nucleation instead of heterogeneous, epitaxial CdS nucleation on CdSe, leading to broad and multimodal particle size distributions. Critically, obtained core/shell sizes are often below those desired. This article describes synthetic conditions specific to thick-shell growth (n> 10 and n> 20 MLs) on both small (sub2 nm) and large (>4.5 nm) CdSe cores. We find added secondary amine and low concentration of CdSe cores and molecular precursors give desired core/shell sizes. Amine-induced, partial etching of CdSe cores results in apparent shell-thicknesses slightly beyond those desired, especially for very-thick shells (n >20 MLs). Thermal ripening and fast precursor injection lead to undesired homogeneous CdS nucleation and incomplete shell growth. Core/shells derived from small CdSe (1.9 nm) have longer PL lifetimes and more pronounced blinking at single-particle level compared with those derived from large CdSe (4.7 nm). We expect our new synthetic approach will lead to a larger throughput of these materials, increasing their availability for fundamental studies and applications.
Copyright Owner
American Chemical society
Copyright Date
2011
Language
en
File Format
application/pdf
Recommended Citation
Guo, Yijun; Marchuk, Kyle; Sampat, Siddharth; Abraham, Rachel; Fang, Ning; Malko, Anton V.; and Vela, Javier, "Unique challenges accompany thick-shell CdSe/nCdS (n > 10) nanocrystal synthesis" (2011). Chemistry Publications. 133.
https://lib.dr.iastate.edu/chem_pubs/133
Comments
Reprinted (adapted) with permission from Journal of Physical Chemistry C 116 (2012): 2791, doi: 10.1021/jp210949v. Copyright 2011 American Chemical Society.