Distance-Dependent Energy Transfer under Modal Strong Coupling from CdSe/ZnS Quantum Dots to a Plasmonic Fabry–Pérot Cavity

Semiconductor quantum dots (QDs) and plasmonic metal nanoparticles (PMNPs) have interesting but different physical and optical properties. The combination of QDs and PMNPs modifies QD's excitonic and charge carrier properties, introducing inimitable optical properties and opening many plasmon-enhanced photonic applications. The modal strong coupling between the localized surface plasmon resonance of Au NPs and the optical mode of the Fabry–Pérot cavity enhances energy transfer between QDs and Au NPs. By combining helicon sputter coating and atomic layer deposition, we fabricate an Au NPs/TiO2/Au film (ATA) Fabry–Pérot cavity that abstracts the excitation energy of CdSe/ZnS QDs placed at 3 to 80 nm from the cavity, where atomistically precise alumina films control the cavity–QD distance. Steady-state and time-resolved absorption and photoluminescence measurements help us to reveal long-range (>80 nm), modal-strong-coupled nonradiative deactivation of photoexcited QDs.