Chiral Self‐Assembled Film from Semiconductor Nanorods with Ultra‐Strong Circularly Polarized Luminescence

• Published in: Angewandte Chemie Vol. 133; no. 50; pp. 26480 - 26484
• Main Authors: Chen, Lijing, Hao, Changlong, Cai, Jiarong, Chen, Chen, Ma, Wei, Xu, Chuanlai, Xu, Liguang, Kuang, Hua
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 06.12.2021
• Subjects: Birefringence; Cadmium selenides; Cadmium sulfide; Chemistry; chirality; Circular dichroism; Circular polarization; circularly polarized luminescence; Dichroism; Fabrication; Luminescence; Nanomaterials; Nanorods; Nanotechnology; Optical activity; self-assembled film; semiconductor nanorods
• DOI: 10.1002/ange.202112582
• ISSN: 0044-8249

Chiroptical nanomaterials have generated significant levels of interest for generating strong circularly polarized luminescence (CPL) signals. We used the Langmuir–Schaeffer technique to generate the continuous and compact assembly of CdSe/CdS chiral film. We assembled achiral CdSe/CdS nanorods by controlling the number of layers and angles between different layers. This allowed us to tailor chiroptical properties to achieve high CPL signals. The chiral film was symmetrical and had the highest circular dichroism (CD) response and CPL signals with ten layers (RH (right‐handed)‐/LH (left‐handed)‐5 + 5 layers) and a 45° inter‐angle. Specifically, RH‐5+5 of the chiral film exhibited 1431 mdeg of CD activity and strong CPL signals with a dissymmetry factor (glum) of 0.0997. The helical stacked crystal plates with linear birefringence resulted in strong circular birefringence, as determined by the Reusch model. Electromagnetic simulations indicated that such remarkable optical activity was attributed to the birefringence and dichroism of the well‐aligned CdSe/CdS nanorod layers in the chiral films. Under right/left circular polarized (RCP/LCP) light excitation, the well aligned semiconductor nanorods exhibited differences in the coupling efficiencies to RCP and LCP light. Our CdSe/CdS chiral films, which exhibit ultra‐strong CPL activity, will provide a novel strategy for the fabrication of chiroptical devices. Achiral CdSe/CdS nanorods were assembled into chiral films using the Langmuir–Schaeffer technique. The CdSe/CdS nanorods films displayed intense circular dichroism response and circularly polarized luminescence signals, which can be adjusted by controlling the number of layers and angles between different layers.