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Title: Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots

Abstract

With increased interest in semiconductor nanoparticles for use in quantum dot solar cells there comes a need to understand the long-term photostability of such materials. Colloidal CdSe quantum dots (QDs) were suspended in toluene and stored in combinations of light/dark and N{sub 2}/O{sub 2} to simulate four possible benchtop storage environments. CdSe QDs stored in a dark, oxygen-free environment were observed to better retain their optical properties over the course of 90 days. The excited state lifetimes, determined through femtosecond transient absorption spectroscopy, of air-equilibrated samples exposed to light exhibit a decrease in average lifetime (0.81 ns) when compared to samples stored in a nitrogen/dark environment (8.3 ns). A photoetching technique commonly used for controlled reduction of QD size was found to induce energetic trap states to CdSe QDs and accelerate the rate of electron-hole recombination. X-ray absorption near edge structure (XANES) analysis confirms surface oxidation, the extent of which is shown to be dependent on the thickness of the ligand shell.

Authors:
; ;  [1]
  1. (Notre)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1047895
Resource Type:
Journal Article
Journal Name:
J. Phys. Chem. C
Additional Journal Information:
Journal Volume: 116; Journal Issue: (24) ; 06, 2012; Journal ID: ISSN 1932-7447
Country of Publication:
United States
Language:
ENGLISH
Subject:
14 SOLAR ENERGY; ABSORPTION; ABSORPTION SPECTROSCOPY; EXCITED STATES; EXCITONS; LIFETIME; OPTICAL PROPERTIES; OXIDATION; QUANTUM DOTS; RECOMBINATION; SOLAR CELLS; STORAGE; THICKNESS; TOLUENE; TRANSIENTS

Citation Formats

Hines, Douglas A., Becker, Matthew A., and Kamat, Prashant V. Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots. United States: N. p., 2012. Web. doi:10.1021/jp303659g.
Hines, Douglas A., Becker, Matthew A., & Kamat, Prashant V. Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots. United States. doi:10.1021/jp303659g.
Hines, Douglas A., Becker, Matthew A., and Kamat, Prashant V. Wed . "Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots". United States. doi:10.1021/jp303659g.
@article{osti_1047895,
title = {Photoinduced Surface Oxidation and Its Effect on the Exciton Dynamics of CdSe Quantum Dots},
author = {Hines, Douglas A. and Becker, Matthew A. and Kamat, Prashant V.},
abstractNote = {With increased interest in semiconductor nanoparticles for use in quantum dot solar cells there comes a need to understand the long-term photostability of such materials. Colloidal CdSe quantum dots (QDs) were suspended in toluene and stored in combinations of light/dark and N{sub 2}/O{sub 2} to simulate four possible benchtop storage environments. CdSe QDs stored in a dark, oxygen-free environment were observed to better retain their optical properties over the course of 90 days. The excited state lifetimes, determined through femtosecond transient absorption spectroscopy, of air-equilibrated samples exposed to light exhibit a decrease in average lifetime (0.81 ns) when compared to samples stored in a nitrogen/dark environment (8.3 ns). A photoetching technique commonly used for controlled reduction of QD size was found to induce energetic trap states to CdSe QDs and accelerate the rate of electron-hole recombination. X-ray absorption near edge structure (XANES) analysis confirms surface oxidation, the extent of which is shown to be dependent on the thickness of the ligand shell.},
doi = {10.1021/jp303659g},
journal = {J. Phys. Chem. C},
issn = {1932-7447},
number = (24) ; 06, 2012,
volume = 116,
place = {United States},
year = {2012},
month = {11}
}