Lehouelleur Henri, Po Hong, Makké Lina, Fu Ningyuan, Curti Leonardo, Dabard Corentin, Roux-Byl Céline, Baptiste Benoit, Van Zee Nathan J, Pons Thomas, Lhuillier Emmanuel, Li Jing, Ithurria Sandrine
Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS, 10 rue Vauquelin, 75005 Paris, France.
Sorbonne Université, CNRS, Institut de minéralogie, de physique des matériaux et de cosmochimie, IMPMC, F-75005 Paris, France.
J Am Chem Soc. 2024 Nov 13;146(45):30871-30882. doi: 10.1021/jacs.4c08981. Epub 2024 Nov 3.
Group II-VI semiconductor nanoplatelets (NPLs) with atomically defined thicknesses and extended atomically flat (001) facets are used for ligand binding and chiro-optical effects. In this study, we demonstrate that tartrate ligands, anchored by two carboxylate groups, chelate the (001) facets of NPLs at an average ratio of one tartrate molecule to two cadmium (Cd) surface atoms. This assembly of chiral molecules on inorganic nanocrystals generates a circular dichroism -factor as high as 1.3 × 10 at the first excitonic transition wavelength of NPLs. Tartrate ligands induce an orthorhombic distortion of the initially "cubic" crystal structure, classifying the NPLs within the 222-point group. Unlike spherical nanocrystals, where it is difficult to discern whether chiral ligands affect only the surface atoms or the entire crystal structure, our findings unequivocally show that the crystal structure of NPLs is modified due to their thinness and atomically precise thickness. The in-plane lattice parameters experience compressive and tensile stresses, significantly splitting the heavy-hole and light-hole bands. Additionally, tartrate ligands adopt different conformations on the NPL surface over time, resulting in dynamic changes in the circular dichroism signal, including an inversion of its sign.
具有原子级定义厚度和扩展的原子级平整（001）晶面的II-VI族半导体纳米片（NPL）用于配体结合和手性光学效应。在本研究中，我们证明由两个羧基锚定的酒石酸配体以一个酒石酸分子与两个镉（Cd）表面原子的平均比例螯合NPL的（001）晶面。这种手性分子在无机纳米晶体上的组装在NPL的第一个激子跃迁波长处产生高达1.3×10的圆二色性因子。酒石酸配体诱导最初“立方”晶体结构的正交畸变，将NPL归类为222点群。与球形纳米晶体不同，在球形纳米晶体中很难辨别手性配体是否仅影响表面原子或整个晶体结构，我们的研究结果明确表明，NPL的晶体结构因其薄度和原子级精确厚度而发生改变。面内晶格参数经历压缩和拉伸应力，显著分裂重空穴和轻空穴能带。此外，酒石酸配体随时间在NPL表面采用不同的构象，导致圆二色性信号的动态变化，包括其符号的反转。
