Cesium Lead Bromide Perovskite Nanocrystals as a Simple and Portable Spectrochemical Probe for Rapid Detection of Chlorides

Abstract The wide spectral tunability of CsPbBr 3 perovskite nanocrystals (NCs) via instantaneous and facile anion exchange, make them a suitable candidate for chloride detection. Rapid anion‐exchange processes between CsPbBr 3 perovskite NCs and different chloride solutions were carried out in ambient conditions. The resultant anion‐exchanged CsPbCl 3‐x Br x NCs preserved the structural properties and exhibited a remarkable blue‐shift in photoluminescence spectra. This form a basis for detection of chloride ions in water. This has been applied with the limit of detection upto 100 μM. The detection strategies were not only limited to the direct addition of chloride solutions to NCs, but also showed a visual colour change under UV light when the chloride solution is drop‐casted on CsPbBr 3 films that are deposited on glass substrates. Furthermore, the detection strategy is established by drop‐casting CsPbBr 3 NCs onto paper strips that are pre‐soaked in chloride solutions. A considerable blue‐shift in fluorimetry proves them to be an excellent sensing medium as practical spectrochemical probes for on‐site detection of chlorides. Based on this, a colour chart and selectivity chart to access the presence of chlorides and their concentration is demonstrated here.