Shell Dependence of Highly Tunable Circular Dichroism in Chiral Hybrid Plasmonic Nanomaterials for Chiroptical Applications

Chiral plasmonic nanomaterials with fascinating physical and chemical properties show emerging chirality-dependent applications in photonics, catalysis, and sensing. The capability to precisely manipulate the plasmonic chirality in a broad spectral range plays a crucial role in enabling the applications of chiral nanomaterials in diverse and complex scenarios; however, it remains a challenge yet to be addressed. Here we demonstrate a strategy to significantly enhance the tunability of circular dichroism (CD) spectra of chiral nanomaterials by constructing core-shell hybrid metal-semiconductor structures with tailored shells. In a typical case, chiral Au@Cu₂O nanostructures exhibit shell-dependent tunable CD signals in both asymmetry factors and band wavelengths. The shell-dependent CD was demonstrated experimentally by CD and single-particle spectroscopy and theoretically through numerical simulations. By deliberately controlling the geometry of the chiral core and the composition of the achiral shell, we show the versatility of our strategy for constructing chiral hybrid nanostructures with increasing architectural and compositional complexity as well as enhanced plasmonic chirality. Furthermore, the chiral Au@Cu₂O nanostructure exhibits intriguing asymmetric color modulation. This work opens an advancing strategy and provides an important knowledge framework for the rational design of multifunctional chiral hybrid nanostructures toward emerging chirality-dependent applications.