Issue 10, 2013
From the journal:

Journal of Materials Chemistry C

Sulfur-incorporated carbon quantum dots with a strong long-wavelength absorption band†

Woosung Kwon,a   Jongchul Lim,b   Jinuk Lee,a   Taiho Park*b  and  Shi-Woo Rhee*a  

* Corresponding authors

a System on a Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea
E-mail: srhee@postech.ac.kr
Fax: +82-54-279-8619
Tel: +82-54-279-2265

b Polymer Chemistry & Electronics Laboratory, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea
E-mail: taihopark@postech.ac.kr
Fax: +82-54-279-5295
Tel: +82-54-279-2394

Abstract

In this work, we synthesize sulfur-incorporated carbon quantum dots (S-CQDs) and report the effect of sulfur on their electronic structure. Sulfur provides the density of states or emissive trap states for photoexcited electrons, and hence improves absorbance and photoluminescence intensity in the long-wavelength (∼500 nm) regime. The formation of the emissive trap states in the band-gap is confirmed by time-resolved emission decay spectroscopy. It is revealed that the emissive trap states prolong the fluorescence lifetime of low energy (∼2.5 eV) photoexcited electrons. To explore further the change in the band-gap energy, we demonstrate charge transport in S-CQD films that serve as the channels of field-effect transistors (FETs). The turn-on voltage of the S-CQD-based FETs decreases with the increase of the sulfur concentration, which is consistent with the optical changes. Our results establish a technical basis to incorporate heterogeneous atoms into CQDs and examine the related changes made to their optoelectronic properties. This method would open up new prospects to control the band-gap energy of CQDs in mild conditions, and hence promote their applications in imaging agents and optoelectronic devices.

Graphical abstract: Sulfur-incorporated carbon quantum dots with a strong long-wavelength absorption band

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Article information

DOI
https://doi.org/10.1039/C3TC00683B
Article type
Paper
Submitted
21 Nov 2012
Accepted
10 Jan 2013
First published
11 Jan 2013

J. Mater. Chem. C, 2013,1, 2002-2008

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Sulfur-incorporated carbon quantum dots with a strong long-wavelength absorption band

W. Kwon, J. Lim, J. Lee, T. Park and S. Rhee, J. Mater. Chem. C, 2013, 1, 2002 DOI: 10.1039/C3TC00683B

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