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Davina Moodelly

Synthesis and characterization of chalcopyrite and Ag2S fluorescent nanocrystals

Published on 25 February 2020
Thesis presented February 25, 2020

Since their discovery in the 1980s, quantum dots or fluorescent nanocrystals of semiconductor materials have attracted a lot of attention thanks to their exceptional photophysical properties easily scalable according to their sizes and compositions. First to be discovered, binary quantum dots like CdS, CdSe, and PbS are the most studied for potential optoelectronic applications in LEDs or photovoltaics. It was not until 1998 that the first biomedical applications of CdSe/CdS and CdSe/ZnS core/shell quantum dots were used in vitro as biological probes. Although these QDs have excellent optoelectronic properties, they contain toxic heavy metals. The toxicity of these binary compounds has been demonstrated both on cells (cytotoxicity) and on DNA (genotoxicity). Their application in electronic components is restricted by the European directive RoHS (Restrictions of hazardous substances). It is therefore necessary to replace these toxic heavy metals with less toxic or non-toxic elements if they are to be used biological probes. Ternary quantum dots containing copper (CuInS2) or silver (AgInS2) as well as the binary compound Ag2S are promising alternatives that can cover emission ranges from the visible to the infrared region. This thesis describes synthesis methods devised to obtain quantum dots of CuInS2, AgInS2 (visible emission) and Ag2S (infrared emission) directly in water and the possible applications of these compounds as biological probes and for biomedical imaging.

Quantum dots, Bio-detection, Cadmium-free

On-line thesis.