Insight into the mechanism of the photoluminescence of carbon nanoparticles derived from cryogenic studies

The unexpected discovery of the photoluminescence of carbon nanoparticles attracted the attention of many researchers and resulted in their use in a variety of applications. However, the origin of their emission is still obscure, and the majority of the discussions on the subject focus on their mole...

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Bibliographic Details
Published inNanoscale Vol. 1; no. 19; pp. 932 - 9328
Main Authors Malyukin, Yuriy, Viagin, Oleg, Maksimchuk, Pavel, Dekaliuk, Mariia, Demchenko, Alexander
Format Journal Article
LanguageEnglish
Published England Royal Society of Chemistry 17.05.2018
Subjects
Carbon
Dependence
Emission
Excitation spectra
Excitons
Fluorescence
Molecular chains
Molecular relaxation
Nanoparticles
Overheating
Phosphorescence
Photoluminescence
Service life assessment
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Summary:The unexpected discovery of the photoluminescence of carbon nanoparticles attracted the attention of many researchers and resulted in their use in a variety of applications. However, the origin of their emission is still obscure, and the majority of the discussions on the subject focus on their molecular and/or excitonic emissive states. We performed cryogenic studies down to 10 K and did not observe any signatures of suppressed molecular relaxation - the spectra remained broad, showing large unaltered Stokes shifts and temperature-independent emission intensities and lifetimes below 80 K with a weak dependence above this value. We demonstrated that the most general features of carbon nanoparticles, the very large Stokes shifts and considerable differences between the absorption and excitation spectra, are the result of the formation of a dynamic defect, the self-trapped Frenkel exciton. It looks like the distorted domain of the H-aggregate due to the exciton-lattice interaction and the local overheating caused by the exciton relaxation. In addition, at low temperatures the long-lifetime spectral component was found and was attributed to phosphorescence. The obtained results strongly support the excitonic nature of the fluorescence of nanocarbon materials. The origin of the fluorescence of carbon dots is the formation of self-trapped excitons in H-aggregate-like structures.
Bibliography:10.1039/c8nr02296h
Electronic supplementary information (ESI) available. See DOI
ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:2040-3364
2040-3372
2040-3372
DOI:10.1039/c8nr02296h