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Author Notes:

Email: Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA . Email: tlian@emory.edu

K. Wu and G. Liang contributed equally to this work.

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Research Funding:

T.L. acknowledge the financial support from the National Science Foundation (CHE-1309817)

J.R.M. acknowledges funding by the National Science Foundation (CHE-1213758).

STEM and EDS images were acquired using an FEI Tecnai Osiris electron microscope supported by the National Science Foundation (EPS-1004083).

Quasi-type II CuInS2/CdS core/shell quantum dots

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Journal Title:

Chemical Science

Volume:

Volume 7, Number 2

Publisher:

, Pages 1238-1244

Type of Work:

Article | Final Publisher PDF

Abstract:

Ternary chalcopyrite CuInS2 quantum dots (QDs) have been extensively studied in recent years as an alternative to conventional QDs for solar energy conversion applications. However, compared with the well-established photophysics in prototypical CdSe QDs, much less is known about the excited properties of CuInS2 QDs. In this work, using ultrafast spectroscopy, we showed that both conduction band (CB) edge electrons and copper vacancy (VCu) localized holes were susceptible to surface trappings in CuInS2 QDs. These trap states could be effectively passivated by forming quasi-type II CuInS2/CdS core/shell QDs, leading to a single-exciton (with electrons delocalized among CuInS2/CdS CB and holes localized in VCu) half lifetime of as long as 450 ns. Because of reduced electron-hole overlap in quasi-type II QDs, Auger recombination of multiple excitons was also suppressed and the bi-exciton lifetime was prolonged to 42 ps in CuInS2/CdS QDs from 10 ps in CuInS2 QDs. These demonstrated advantages, including passivated trap states, long single and multiple exciton lifetimes, suggest that quasi-type II CuInS2/CdS QDs are promising materials for photovoltaic and photocatalytic applications.

Copyright information:

© 2016 The Royal Society of Chemistry.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/).

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