Precise Ligand Tuning Emission of Mn-Doped CsPbCl Nanocrystals by the Amount of Sulfonates.

Using Mn-doped CsPbCl nanocrystals (Mn:CsPbCl NCs) to improve perovskite's properties is becoming an important strategy. Here, we demonstrate a modified supersaturated recrystallization route to synthesize high-quality Mn:CsPbCl NCs at room temperature. Unprecedentedly, sulfonate ligands with various concentrations are shown to successfully tune the dual-color emission of Mn:CsPbCl NCs. Ultrafast transient absorption studies reveal that the host-to-dopant internal energy-transfer process involves the mediated traps. Interestingly, the dual-color emission is tuned via stabilizing mediated traps with a small amount of ligand (band edge (BE) emission reduces and Mn emission increases), passivating the deep traps with a large amount of ligand (Mn emission increases), and destroying Mn:CsPbCl NCs with too much ligand (both BE and Mn emission is quenched). Furthermore, the ligand tuning Mn emission exhibits quenching for Cu with high sensitivity and selectivity. Our work provides a new strategy to tune the optical properties of Mn:CsPbCl NCs and presents its potential application in an optical detector.