Towards Luminescent Water-Dispersible CdSe@CdS Nanorods with High pH-Stability
Bei Liu a, Mathias Micheel a, Maria Wächtler a
a Leibniz Institute of Photonic Technology, Department Functional Interfaces, Albert Einstein Straße 9, 07745 Jena, Germany
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#NCFun19. Fundamental Processes in Semiconductor Nanocrystals
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Ivan Infante and Jonathan Owen
Poster, Bei Liu, 400
Publication date: 18th July 2019

Water-dispersible CdSe@CdS semiconductor nanorods, which may act as photosensitizer in the hydrogen evolution reaction, are readily available by using 11-mercaptoundecanoic acid (MUA) as surface ligand. However, their colloidal instability at acidic values presents a drawback for their application under real conditions. Another disadvantage of MUA is hole trapping induced by the thiol group binding to the surface, reflected in decreased photoluminescence.

In this work, we aim to increase the colloidal stability of water-dispersible nanorods in a wide range of pH values. We employed different kinds of capping ligands, namely dihydrolipoic acid–polyethylene glycol (DHLA–PEG), mercaptopolyethylene glycol monomethyl ether (PEG–SH), and polyethyleneimine (PEI). Nanorods capped with PEI showed a comparatively high photoluminescence quantum yield (PLQY) in water, but were unstable at acidic pH, while nanorods capped with DHLA-PEG demonstrated the opposite behaviour: excellent colloidal pH stability but poor PLQY in pure water. Only nanorods with PEG–SH as surface ligands exhibited both good colloidal stability and reasonable PLQY in water and both neutral and acidic buffer solution. Further, to elucidate the exciton relaxation behaviour in nanorods with different surface functionalization, time-resolved photoluminescence and transient absorption measurements are performed.

Financial support is acknowledged by China Scholarship Council (CSC), the German Research Foundation (DFG) –project number 364549901 - TRR234 [CataLight, B4)] and the Fonds der Chemischen Industrie (FCI).

© Fundació Scito
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