Aqueous-phase preparation of Mn-doped perovskites for three-mode detection of chloride ions in sweat

Mn-doped perovskites have been extensively studied due to their lower heavy metal toxicity and unique optoelectronic properties. However, their intrinsic sensitivity to water limits the extending applications. Besides, the synthesis methods of Mn-doped perovskite still need to be completed in non-polar solvents, which will also cause environmental pollution. Developing new methods will help solve these problems. In this work, we have developed a method for the synthesis of Mn-doped perovskites in aqueous solution. The synthesized perovskites possess excellent stability in water and can be directly dispersed in water without any post-treatment. The perovskites have two photoluminescence peaks belonged to exciton transition and Mn 2+ transition respectively, resulting in diverse color variations during the fast anion exchange process. Based on this, a Mn:CsPb(Cl/Br) 3 based chloride probe is designed. The probe is able to achieve quantitative detection of chloride ion through wavelength shift and photoluminescence intensity ratio, with detection limits of 26.7 μM and 67 μM, respectively. Besides, visual detection is also achieved with limitation of 0.5 mM. This three-mode probe effectively addresses the requirements for both accurate quantification and visual identification of chloride ions, demonstrating the vast potential of perovskites in biosensing.