Mn-doped CsPbCl3 perovskite quantum dots: A dual-function probe for copper detection and temperature sensing

The low photoluminescence quantum yield (PLQY) of CsPbCl3 perovskite quantum dots (PQDs) poses a significant challenge to their application as ion detection probes. To address this issue, we enhanced the PLQY of CsPbCl3 PQDs through Mn doping. These enhanced PQDs were then employed as probes for the highly sensitive detection of Cu2+ ions and temperature. CsPbCl3:Mn PQDs with varying Mn/Pb ratios were synthesized via hot injection. The Mn doping introduced an emission band near 600 nm, with intensity increasing alongside doping concentration. At an Mn/Pb ratio of 2.0, the PLQY was enhanced nearly tenfold, from 5.46 % for undoped CsPbCl3 to 52.48 % for CsPbCl3:Mn. CsPbCl3:Mn PQDs with the highest PLQY were employed as luminescent probes, utilizing the fluorescence intensity ratio (FIR) technique for copper detection and temperature sensing. The experimental results demonstrated a linear relationship between the FIR and Cu2+ concentration over the range of 22.12 nM-1600 nM, with 22.12 nM being the calculated limit of detection. Analysis of the emission spectra and fluorescence lifetimes at varying Cu2+ concentrations revealed that electron transfer from CsPbCl3 to Cu2+ induced fluorescence quenching. CsPbCl3:Mn exhibits a high relative sensitivity of 15.89 % K-1 at 298 K, along with excellent reversibility. These findings highlight the potential application of CsPbCl3:Mn PQDs in both temperature sensing and the analysis of wear metals in engine lubricating oils.