Probing Excitons in Ultrathin PbS Nanoplatelets with Enhanced Near-Infrared Emission

Journal article (2021)

Authors

Qianli Yu Student
Lars F. Klepzig Leibniz Universität
L.D.A. Siebbeles ChemE/Opto-electronic Materials - AS
R.W. Crisp Friedrich-Alexander-Universität Erlangen-Nürnberg, ChemE/Opto-electronic Materials - AS
J.D. Lauth ChemE/Opto-electronic Materials - AS , Leibniz Universität
Research Group
ChemE/Opto-electronic Materials (AS) (TU Delft)
Copyright: © 2021 Francisco Manteiga Vázquez, Qianli Yu, Lars F. Klepzig, L.D.A. Siebbeles, R.W. Crisp, J.D. Lauth
DOI: https://doi.org/10.1021/acs.jpclett.0c03461
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Published Date

2021

Language

English

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Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Opto-electronic Materials

Abstract

Colloidal PbS nanoplatelets (NPLs) are highly interesting materials for near-infrared optoelectronic applications. We use ultrafast transient optical absorption spectroscopy to study the characteristics and dynamics of photoexcited excitons in ultrathin PbS NPLs with a cubic crystal structure. NPLs are synthesized at near room temperature from lead oleate and thiourea precursors; they show an optical absorption onset at 680 nm (1.8 eV) and photoluminescence at 720 nm (1.7 eV). By postsynthetically treating PbS NPLs with CdCl2, their photoluminescence quantum yield is strongly enhanced from 1.4% to 19.4%. The surface treatment leads to an increased lead to sulfur ratio in the structures and associated reduced nonradiative recombination. Additionally, exciton-phonon interactions in pristine and CdCl2 treated NPLs at frequencies of 1.96 and 2.04 THz are apparent from coherent oscillations in the transient absorption spectra. This study is an important step forward in unraveling and controlling the optical properties of IV-VI semiconductor NPLs.

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