A New Method for Characterizing Chiral Materials Based on Second Harmonic Circular Dichroism Spectroscopy

Recently, the internationally renowned journal "Nano Letters" published online a paper titled "Regulating Optical Activity and Anisotropic Second-Harmonic Generation in Zero-Dimensional Hybrid Copper Halide" by Professor Wang Changshun's group from the School of Physics and Astronomy, Shanghai Jiao Tong University
.

This work provides a new idea for regulating the optical activity and anisotropic second-harmonic generation of chiral metal halides, and proposes a new method to characterize chiral materials based on second-harmonic circular dichroism spectroscopy

Fig.

1 Schematic diagram of the second harmonic circular dichroism of chiral hybrid copper-based halides

Chiral materials have recently attracted widespread attention in interdisciplinary fields due to their mirror-image asymmetry, and have shown attractive development prospects in applications such as 3D display, asymmetric synthesis, chiral sensing, and chiral optoelectronics.

.

As an emerging class of semiconductor materials, organic-inorganic hybrid metal halides exhibit flexible tunability in their structure and composition, which provides the possibility to further extend their excellent optoelectronic properties to chiral optoelectronics

Figure 2 Schematic diagram of the lattice structures of chiral enantiomer molecules and chiral hybrid copper-based halides

To solve the above problems, the researchers chose two types of chiral organic enantiomeric cations to assemble with copper chloride, and prepared chiral thin films crystallized in different space groups by a one-step solution-processed spin-coating method
.

Although the inorganic building blocks of the two pairs of thin-film materials are compositionally similar, the two chiral hybrid copper-based halides exhibit significant differences in optical activity, which further analysis confirms can be attributed to their magnetic transition dipole moments difference

Fig.
3 Linear and circular polarization resolved second harmonics of chiral hybrid copper-based halide

This research is the result of the co-authored paper "Giant Optical Activity and Second Harmonic Generation in 2D Hybrid Copper Halides, Angew.
Chem.
Int.
Ed.
(2021) 60 (15): 8441-8445, (IF: 15.
336) On the basis of ", by further selecting the chiral organic enantiomer, the effective control of the optical activity and the anisotropic second harmonic is realized
.

Chiral hybrid metal halides are well suited for designing novel photonic devices due to their unique second-order nonlinear optical response and second-harmonic circular dichroism factor

In this paper, Guo Zhihang, a doctoral student of Shanghai Jiaotong University, and Li Junzi, a doctoral student of Shenzhen University, are the co-first authors, and Professor Wang Changshun, Professor He Tingchao of Shenzhen University, and Assistant Professor Zhu Xi of the Chinese University of Hong Kong (Shenzhen) are the co-corresponding authors
.

This research work was supported by the National Natural Science Foundation of China Major Research Program (92050116), the Shenzhen Basic Research Project (CYJ20190808121211510, JCYJ20210324094414039) and the Guangdong Provincial Department of Education's Characteristic Innovation Project (2018KTSCX198)

Paper link : https://pubs.

author:

Ye Dan

Contributing unit:

School of Physics and Astronomy