IR luminescence of plexcitonic structures based on Ag₂S/L-Cys quantum dots and Au nanorods

The luminescence properties of Ag₂S quantum dots passivated with L-Cysteine (Ag₂S/L-Cys QDs) are studied in the presence of Au nanorods passivated with cetyltrimethylammonium bromide molecules (Au/CTAB NRs). The effect of plasmonic Au/CTAB NRs on IR trap state luminescence (750 nm) is considered. It has been found that the direct interaction between the components of the plexcitonic nanostructure leads to a significant luminescence quenching of Ag₂S/L-Cys QDs, with the luminescence lifetime being constant. This is the evidence for photoinduced charge transfer. The spatial separation of the components of plexcitonic nanostructures due to the introduction of a polymer - Poly(diallyldimethylammonium chloride) (PolyDADMAC) provides a means to change their mutual arrangement and achieve an increase in the IR trap state luminescence intensity and a decrease in the luminescence lifetime from 7.4 ns to 4.5 ns. With weak plexcitonic coupling in the nanostructures [Ag₂S QD/L-Cys]/[PolyDADMAC]/[Au/CTAB NRs], the possibility of increasing the quantum yield of trap state luminescence for Ag₂S QDs due to the Purcell effect has been demonstrated.