Optically Active\nPerovskite CsPbBr₃ Nanocrystals\nHelically Arranged on Inorganic Silica Nanohelices

Abstract

Perovskite\nnanocrystals (PNCs) exhibit excellent absorption and\nluminescent properties. Inorganic silica right (or left) handed nanohelices\nare used as chiral templates to induce optically active properties\nto CsPbBr₃ PNCs grafted on their surfaces. In suspension,\nPNCs grafted on the nanohelices do not show any detectable chiroptical\nproperties. In contrast, in a dried film state, they show large circular\ndichroism (CD) and circularly polarized luminescence (CPL) signals\nwith dissymmetric factor up to 6 × 10^–3. Grazing\nincidence X-ray scattering, tomography, and cryo-electron microscopy\n(EM) have shown closely and helically packed PNCs on the dried helices\nand much more loosely organized PNCs on helices in suspension. Simulations\nbased on the coupled dipole method (CDM) demonstrate that the CD comes\nfrom the dipolar interaction between PNC assembled into a chiral structure\nand the CD decreases with the interparticle distance.