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.