Fano resonance in the CsPbBr3 nanocrystal/Ag nanostructure through the exciton-plasmon coupling

Abstract

Fano resonance (FR) has attracted more attention recently due to its outstanding properties, such as coherent interference at the resonant energy and intense changes in the spectral lines. Here, we studied the FR effects in the CsPbBr3 nanocrystal (NC)/Ag nanostructure coupling structure. The FR effects cause asymmetric line shapes in both the reflection and transmission spectra. A sharp variation was observed in the spectral line at the exciton energy of CsPbBr3 NC. The FR in this coupling structure is attributed to the configuration interaction between the exciton state and the surface plasmon (SP) states. From the coupling theory, we suggest that it is necessary to consider multiSP states in the interaction Hamiltonian, instead of a single SP state, which will induce more interesting effects. Moreover, we demonstrate that the FR effects are sensitively dependent on the spacing in the coupling structure. The sharp variation of the spectral line shape at the resonant energy and its sensitivity on the spacing in the coupling structure make the FR effects an important candidate as the optical monitoring methods in the application of real time artificial tunable optoelectronic device at the nanoscale.