The Luminescence of Laser-Produced Carbon Nanodots: The Effect of Aggregation in PEI Solution

Autor: Agata Kaczmarek, Agnieszka Wisniewska, Tomasz Mościcki, Jacek Hoffman
Jazyk: angličtina
Rok vydání: 2024
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Zdroj: Materials, Vol 17, Iss 7, p 1573 (2024)
Druh dokumentu: article
ISSN: 1996-1944
DOI: 10.3390/ma17071573
Popis: Carbon nanodots (CNDs) produced in pure water by the ablation of graphite with a nanosecond laser pulse exhibit weak photoluminescence. A small addition of polyethyleneimine (PEI) to the aqueous suspension of CNDs causes a significant increase in emissions. This paper presents experimental and theoretical studies of the emission properties of CND/PEI systems. The obtained CNDs responded to even trace amounts of PEI in solution (~0.014% v/v), resulting in a significant increase in the initial weak blue emission of CNDs and PEI taken separately. Morphology and size measurements showed that particle aggregation occurred in the presence of the polymer. A decrease in the calculated Stokes shift values was observed with increasing PEI content in the solution. This indicates a reduction in the number of non-radiative transitions, which explains the increase in the emission intensity of the CND/PEI systems. These results therefore confirmed that the increase in the emission of CND/PEI systems is caused by particle aggregation. Kinetic studies proved that the process is controlled mainly by diffusion, the initial stage of which has a dominant influence on determining the optical properties of the system.
Databáze: Directory of Open Access Journals
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