Unprecedented Intrinsic Chirality in CsPbBr3 Nanoplatelets Tunable Through Synthetic Conditions

This work reports on the intrinsic chiral behavior in colloidal ultrathin CsPbBr3 nanoplatelets with unprecedent quantitative s-handed value as studied using circular dichroism measurements. Through adjusting various synthetic parameters, such as temperature, Cs and Pb reagent ratios, reaction solvents and stirring direction, we are able to tune the quantitative chiral properties in these nanomaterials. Additionally, the functional aspects such as the handedness of these nanoplatelets can be tuned using brominated methylbenzylamines with suitable r/s chirality. We utilize the advantageous procedure of single particle photoluminescence studies to attain insights into the lifetimes and correlate them with the presence and the type of ligands. We reach qualitative arguments based on surface defects and Pb extraction through selected area electron microscopy, and rigorous x-ray diffraction accompanied with Rietveld refinement analyses- to explain the atomic arrangements at the surface of these nanoplatelets which can be tuned through synthetic factors. Optical characterization by absorption and circular dichroism extends these ideas into correlation with microscopy and diffraction results. These remarkable control of chiral parameters without external stimuli in untreated/as prepared nanoplatelets; and through choice of the ligation combinations hence accomplished highlight the suitability of these ultrathin CsPbBr3 nanoplatelets for applications in a wide range of optical and mechanical applications including chiral superstructures.