Giant Optical Activity of Quantum Dots, Rods and Disks with Screw Dislocations

Abstract

For centuries mankind has been modifying the optical properties of materials: first, by elaborating the geometry and composition of structures made of materials found in nature, later by structuring the existing materials at a scale smaller than the operating wavelength. Here we suggest an original approach to introduce optical activity in nanostructured materials, by theoretically demonstrating that conventional achiral semiconducting nanocrystals become optically active in the presence of screw dislocations, which can naturally develop during the nanocrystal growth. We show the new properties to emerge due to the dislocation-induced distortion of the crystal lattice and the associated alteration of the nanocrystal’s electronic subsystem, which essentially modifies its interaction with external optical fields. The g-factors of intraband transitions in our nanocrystals are found comparable with dissymmetry factors of chiral plasmonic complexes, and exceeding the typical g-factors of chiral molecules by a factor of 1000. Optically active semiconducting nanocrystals—with chiral properties controllable by the nanocrystal dimensions, morphology, composition and blending ratio—will greatly benefit chemistry, biology and medicine by advancing enantiomeric recognition, sensing and resolution of chiral molecules.

Chiral MoS2 Quantum Dots: Dual‐Mode Detection Approaches for Avian Influenza Viruses

“…Meanwhile, advancement of novel nanofabrication techniques has also enabled the creation of chiral nanostructures which exhibit not only a high amount of circular dichroism (CD) and optical rotatory dispersion, but also extensively enhances the signals obtained from target molecules, which in principle provides a sufficient method to detect with a very high sensitivity . In particular, optical chirality integrated with fluorescence in a nanosystem represents an attractive area of research and has received a great deal of attention because of its potential for optically active components in devices and its ability to offer a wide range of research and development possibilities in diverse areas of physics, chemistry, and life sciences . Chiral fluorescent nanomaterials may exhibit strong coupling with incident photons and can potentially lead to unusual optical responses that are essential for chiral and fluorescence sensing as well as other optical devices.…”

Completely Chiral Optical Force for Enantioseparation

“…This is true for all kinds of chiral nanoparticles, which are nowadays produced in great variety using the emerging fabrication techniques345. Among them are semiconductor nanocrystals with screw dislocations67 or chiral surfaces8910111213. Much like enantiomeric molecules, chiral nanocrystals feature significantly different interactions with biomolecules and biological tissues14.…”

Intraband optical activity of semiconductor nanocrystals

“…For example, a crystal lattice of a semiconductor material can be inherently chiral, as in α‐HgS, which automatically results in optical activity of the nanocrystals made from such a semiconductor . The crystal lattice can be chirally distorted during the nanocrystal growth by screw dislocations and Eshelby twists . Introduction of various impurities into a nanocrystal also distorts its crystal lattice and can break the nanocrystal's mirror symmetry .…”