Temperature Driven Plasmon-Exciton Coupling in Thermoresponsive Dextran-Graft-PNIPAM/Au Nanoparticle/CdTe Quantum Dots Hybrid Nanosystem

The temperature-driven plasmon-exciton coupling in thermoresponsive dextran-graft-PNIPAM/Au nanoparticle/CdTe quantum dot (D-g-PNIPAM/Au NPs/CdTe QDs) hybrid nanosystem was studied. A significant (0.84 eV) splitting of the absorption peak was observed in the absorption spectrum of the nanosystem, which reflects the fact of formation of plexcitons, occurring due to strong plasmon-exciton coupling. An increasing with time plasmonic enhancement of the photoluminescence of CdTe QDs was revealed, as a result of the penetration of quantum dots into the volume of the D-g-PNIPAM/Au NP hybrid nanosystem and bonding to it. The heating-cooling cycle of the aqueous solution of the studied nanosystem leads to a reversible quenching-recovery alteration of the QD photoluminescence. The quenching was rationalized as a result of an increased probability of nonradiative resonance energy transfer (RET) from CdTe QDs to Au NPs, which occurs due to shortening of the NP-QD distance, caused by shrinking of the macromolecule due to cooling-induced lower critical solution temperature phase transition. Increasing the NP-QD distance in the heating stage recovers the QD PL intensity. The observed effect opens up opportunities for the controlled reversible temperature-driven tuning of the photoluminescence intensity of D-g-PNIPAM/Au NP/CdTe QD nanosystem, which is highly important for its potential use in photonics and biomedical applications.

Automated summary

The study focused on temperature-driven plasmon-exciton coupling in a hybrid nanosystem. Significant peak splitting in the absorption spectrum indicated the formation of plexcitons, while plasmonic enhancement of CdTe QDs' photoluminescence was observed over time. The reversible alteration of QD photoluminescence during heating-cooling cycles was attributed to nonradiative resonance energy transfer.