Ligand-Induced Chiroptical Properties in Nanocrystals with Different Core-Shell Band Structures

Chiral semiconductor nanocrystals (NCs) represent a promising class of materials for various applications, including biological sensing, photonics, and spin-polarized devices. However, the comprehension of the mechanisms underlying ligand-induced chiroptical effects in NCs has been limited by the constraints of current theoretical and experimental models, particularly those involving simple spherical NCs. In this study, we examined the relationship between optical activity and band structures in core-shell dot-in-rod NCs, specifically CdSe@CdS, ZnSe/CdS@CdS, and ZnSeTe/CdS@CdS dot-in-rod NCs, which were functionalized with chiral ligands. By manipulating the wave function distribution of electrons and holes within the dot-in-rod NCs, we demonstrated through circular dichroism (CD) measurements that a reduction in the number of holes within the synthesized dot-in-rod NCs correlates with a decrease in the g factor. This conclusion was corroborated by theoretical calculations. Furthermore, the fabrication of chiral CdS-Au heterojunctions and the application of electron quenchers revealed that the reduction of the g factor also suggests the significant role of electrons in the generation of chirality. Our findings not only enhance the understanding of the fundamental origins of induced chirality effects in semiconductor NCs but also provide a clear methodology for the design of optimal optically active chiral NCs, thereby paving the way for future applications utilizing chiroptical materials.