Highly stable and water dispersible polymer-coated CsPbBr3 nanocrystals for Cu-ion detection in water

Abstract

Recently, CsPbX3 (X = I, Br, Cl) nanocrystals (NCs) have shown huge potential in the fields of various optoelectronic applications. However, the CsPbX3 NCs degrade very rapidly in the presence of water and heat, because of dynamic oleic acid and oleylamine capping ligands. The silica-coated CsPbBr3 NCs are comparatively stable but the synthesis is slightly complicated and needs several hours to complete the reaction process. These silica-coated NCs also tend to agglomerate among themselves, which is unfavorable for display technologies and bioimaging applications. In these regards, we introduce novel polymers [polyvinylpyrrolidone and n-isopropyl acrylamide] along with oleic acid and oleylamine that are encapsulated around the CsPbBr3 NCs during the synthesis procedure at room temperature. Such NCs are highly luminescent in the green spectral region with a maximum photoluminescence quantum yield of up to 93%, have narrower emission spectra, and can easily disperse in water. The size distribution of the polymer-coated NCs becomes more uniform and well-dispersed. The water dispersity and stability of these polymer-coated NCs significantly improved in comparison to the conventional silica-coated NCs. Such water-stable NCs were tested as a luminescent probe for Cu2+-ion detection in water that shows a detection limit of 18.6 μM. These outcomes are very encouraging for futuristic display technologies, bioimaging, and sensing applications.