State‐Dependent Permittivity in Upper and Lower Plexcitons Under Plasmon–Single‐Molecule Strong Coupling
Jindong Ai, Xinyi Fan, Ting Luo, Shihao Feng, Wanying Li, Guanqian Wu, Yanmin Kuang, Tianfeng Li, Jing‐Feng Liu, Renming Liu, Lijun Guo, Lin WuABSTRACT
Plasmon‐exciton strong coupling generates hybrid light‐matter states referred to as upper (UP) and lower (LP) plexcitons at room temperature. Nevertheless, their unique optical responses remain inadequately understood. By employing a plasmon–single‐molecule strong‐coupling platform, we reveal distinct differences in the effective permittivity and local electric field distributions associated with these two states. The LP state exhibits significantly stronger effective permittivity and enhanced electric fields within the nanocavity, leading to increased sensitivity to external excitation. These results underscore the state‐dependent optical properties in single‐molecule plexciton systems and provide a viable pathway for tuning hybrid states for applications in quantum chemistry, single‐molecule sensing, and nanoscale optoelectronic control.