Effect of Mndoping and DDAB-assisted postpassivation on the structural and optical properties of CsPb(Cl/Br)halide perovskite nanocrystals.

Cesium lead halide perovskite (CsPbX; X = Cl, Br, I) nanocrystals showing intense band-edge emission and high photoluminescence quantum yield are known to be a potential candidate for application in optoelectronic devices. However, controlling toxicity due to the presence of Pbin lead-based halide perovskites is a major challenge for the environment that needs to be tackled cautiously. In this work, we have partially replaced Pbwith Mnions in the CsPb(Cl/Br)nanocrystals and investigated their impact on the structural and optical properties. The Rietveld refinement shows that CsPbClBr nanocrystals possess a cubic crystal structure with3̅space group, the Mndoping results in the contraction of the unit cell. The CsPb(Cl/Br): Mn nanocrystals show a substantial change in the optical properties with an additional emission band at ∼588 nm through a d-d transition, changing the emission color from blue to pink. Here, a didodecyldimethylammonium bromide (DDAB) ligand that triggers both anion and ligand exchange in the CsPb(Cl/Br): Mn nanocrystals have been used to regulate the exchange reaction and tune the emission color of halide perovskites by changing the peak position and the PL intensities of band-edge and Mndefect states. We have also shown that oleic acid helps in the desorption of oleylamine capping from the CsPb(Cl/Br): Mn nanocrystal surfaces and DDAB, resulting in the substitution of Clwith Bras well as provides capping with shorter branched length ligand which led to increase in the overall PL intensity by many folds.