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

Kaifeng Wu; Guijie Liang; Degui Kong; Jinquan Chen; Zheyuan Chen; Xinhe Shan; James R. McBride; Tianquan Lian

doi:10.1039/C5SC03715H

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

Kaifeng Wu,‡^a Guijie Liang,‡^b Degui Kong,^c Jinquan Chen,^a Zheyuan Chen,^a Xinhe Shan,^a James R. McBride^d and Tianquan Lian*^a

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* Corresponding authors

^a Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, USA
E-mail: tlian@emory.edu

^b Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Hubei University of Arts and Science, Xiangyang 441053, Hubei Province, P. R. China

^c College of Electronic Engineering, Heilongjiang University, Harbin 150080, P. R. China

^d Department of Chemistry, The Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville TN, USA

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 (V_Cu) 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 V_Cu) 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.

This article is part of the themed collection: Global Energy Challenges: Solar Energy

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Article information

DOI: https://doi.org/10.1039/C5SC03715H
Article type: Edge Article
Submitted: 30 Sep 2015
Accepted: 12 Nov 2015
First published: 12 Nov 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry

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Chem. Sci., 2016,7, 1238-1244

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

K. Wu, G. Liang, D. Kong, J. Chen, Z. Chen, X. Shan, J. R. McBride and T. Lian, Chem. Sci., 2016, 7, 1238 DOI: 10.1039/C5SC03715H

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