Emission properties of quantum dots assembled in the polyelectrolyte multilayer

• Main Author: Yang, Yuxin
• Other Authors: Li Changming
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Chemical engineering::Biotechnology
• Online Access: http://hdl.handle.net/10356/16629
• Institution: Nanyang Technological University

Mercaptosuccinic acid capped CdTe quantum dots (QDs) were assembled on glass substrates modified with polyelectrolyte multilayers (PEMs) consisting of poly(ethylenimine) (PEI), poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS). PEMs were built up via Layer-by-Layer (LbL) technique to form the structure of PEI-(PSS/PDDA)n. The adsorption of QDs on different number of PSS/PDDA bilayer was analyzed using Surface Plasmon resonance (SPR), from which it was found that more QDs were adsorbed on two bilayers of PSS/PDDA compared with that on one. It was further confirmed by the increased photoluminescence (PL) intensity as the number of PSS/PDDA bilayer increases. I also found a great enhancement of PL intensity accompanied by a slight blue-shift of PL spectrum when putting the films/QDs system in water environment, and the PL intensity was found to be related with the ionic strength (NaCl) in aqueous solution. Further assembling of PDDA monolayer or PDDA/PSS bilayer will gradually quench the PL emission of QDs.