Nonresonant Exciton–Plasmon Interaction in Metal–Chalcogenide (Cu x S)/Perovskite (CsPbBr3) Based Colloidal Heterostructure

Heterostructures often exploit exciton–plasmon coupling between two materials to enhance various optical properties, where an essential criterion is the resonant energy coupling between the two materials. Recently, however, it is shown that nonresonant exciton–plasmon interaction can take place in a single semiconductor plasmonic nanomaterial, where the plasmonic and excitonic absorptions share no energy overlap. Here, we design a colloidal heterostructure composed of plasmonic Cu x S and excitonic CsPbBr3, without any spectral overlap to study the nonresonant interaction across two different materials. The heterostructure shows different structural and optical properties such as a strained interface between the two parent components, higher Urbach energy compared to perovskite, and photoluminescence quenching that suggests possible interaction, and its magnetic circular dichroism properties show a clear signature of strong nonresonant exciton–plasmon interaction. To the best of our knowledge, this is the first demonstration of nonresonant exciton–plasmon interaction that can open new possibilities in plasmontronics.