Physical Mechanisms on Absorption and Photoluminescence Properties of Coupled Plasmon-Exciton (Plexciton) Systems

Plexciton is the formation of new hybridized energy states originated from the coupling between a plasmon and an exciton. To reveal the optical properties of both the exciton and plexciton, we develop a classic oscillator model to describe their behavior. Particularly, the coupling case, i.e., plexciton, is investigated theoretically in detail. In strong coupling, the phenomenon similar to electromagnetically induced transparency is achieved for the absorption spectra; the splitting behaviors of the modes are carefully analyzed, and the splitting largely depends on the effective number of electrons and the resonance coupling; the photoluminescence spectra show that the spectral shapes remain almost unchanged for weak coupling and change a lot for strong coupling; and the emission intensity of the exciton is strongly enhanced by the plasmon and can reach the order of 1010 for a general case. We also show the comparisons between our model and the published experiments to validate its validity. This work may be useful for understanding the mechanism of the plexciton and for the development of new applications.

Automated summary

Plexciton is a new hybridized energy state formed by the coupling of a plasmon and an exciton, and its optical properties are described using a classic oscillator model. In the case of strong coupling, absorption spectra show a phenomenon similar to electromagnetically induced transparency, and the splitting behavior of modes depends on the effective number of electrons and resonance coupling. Photoluminescence spectra exhibit significant changes in strong coupling, while the emission intensity of the exciton is greatly enhanced by the plasmon. Comparisons with published experiments validate the model's validity. This study is important for understanding Plexciton mechanism and the development of new applications.