Fabrication of CsPbBr₃ Perovskite Quantum Dots/Cellulose-Based Colorimetric Sensor: Dual-Responsive On-Site Detection of Chloride and Iodide Ions

Cesium lead bromide perovskite quantum dots (PQDs) have recently attracted much attention because of their remarkable optoelectronic properties, such as high photoluminescence quantum efficiency, narrow emission, tunable wavelength, and color purity. However, despite these excellent properties, their instability in the case of prolonged exposure to humidity, pH, and/or temperature limits their applicability. Here, we propose a simple and portable cellulose-based colorimetric sensor integrated with CsPbBr₃ PQDs for the rapid naked-eye detection of chlorine and iodine ions. We synthesized the CsPbBr₃ PQDs/cellulose composite via a hot injection method, which allows the formation of monodispersed CsPbBr₃ PQDs with high sensitivity; given the strong adherence of the CsPbBr₃ PQDs to the porous cellulose fibers, the composite exhibited excellent stability and durability against various humidity conditions along with superior photoluminescence properties. When applying our CsPbBr₃ PQDs/cellulose composite as an early diagnosis sensor, we observed a remarkable color change at a fast rate (within 5 s) after the introduction of the sample solution, resulting from its rapid diffusion into the porous cellulose network, that could be quantified via red, green, and blue imaging analysis. Therefore, the presented CsPbBr₃ PQDs/cellulose composite could be used as an effective colorimetric sensor for the real-Time monitoring of trace elements such as chlorine and iodine in tap water.