Shell-dependent Blinking of CdSe-Based Core/Shell Nanocrystals

Published

May 10, 2010

Author(s)

Seung Koo Shin, Bonghwan Chon, Sung Jun Lim, Wonjung Kim, Hyeong G. Kang, Taiha Joo, Jeeseong C. Hwang

Abstract

Blinking of zinc-blende CdSe-based core/shell nanocrystals are studied as a function of shell materials. CdSe/ZnS, CdSe/ZnSe/ZnS, and CdSe/CdS/ZnS core/shell nanocrystals are prepared by epitaxial growth of two-to-six monolayers (MLs) of shell materials over the same green-emitting CdSe core. The time trace of blinking is recorded for single nanocrystals on a borosilicate cover glass. Both on- and off-time distributions are fit to the power law. The off-time exponents are grouped in the range of 1.45-1.70, whereas the on-time exponents are spread in the range of 1.84-2.11. The on-time duration significantly varies with shell material and thickness. As the thickness of ZnS shell increases from four-to-six MLs in CdSe/ZnS nanocrystals, the on-time duration decreases with concomitant increases in the off-time duration. On the other hand, as the shell composition and structure are changed to CdS(2ML)/ZnS(4ML), the power-law statistics remains almost identical to that of CdSe/ZnS(4ML) nanocrystals; on the contrary, the ZnSe(2ML)/ZnS(4ML) double shell over the CdSe core shortens the on-time duration. The shell-dependent power-law exponents suggest that blinking of single nanocrystals can be suppressed by reducing interfacial defects and extending the conduction band to the shell.

Citation

Physical Chemistry Chemical Physics

Volume

12

Pub Type

Journals

Download Paper

DOI Link

Keywords

quantum dot, nanocrystal, core-shell

Citation

Shin, S. , Chon, B. , Lim, S. , Kim, W. , Kang, H. , Joo, T. and Hwang, J. (2010), Shell-dependent Blinking of CdSe-Based Core/Shell Nanocrystals, Physical Chemistry Chemical Physics, [online], https://doi.org/10.1039/b924917f (Accessed April 19, 2024)