Active control of the photoluminescence emitted by quantum dots using metallic nanoparticles and photochromic molecules

Abstract : Metallic nanoparticles (MNP) may sustain Localized Surface Plasmon (LSP) resonances and the coupling between MNP and quantum dots (QD) is known to lead either to the enhancement or to the quenching of the QD photoluminescence. The distance between QD and MNP is one of the switch parameters between both regimes. The goal of this study is to control the coupling distance (different from the physical distance) between QD and MNP by changing the refractive index of the surrounding medium using photochromic molecules (PM). These molecules are optical switches, which move from a transparent state to a colored one by absorbing UV light. The main drawback concerns the spectral overlap and the lifetime of each optical phenomenon, since the photochromic molecules can couple to LSP to induce strong coupling or couple to QDs to quench the photoluminescence. In this study, we measured photoluminescence spectra, images and lifetimes of QDs deposited on a glass substrate, with or without the presence of MNPs and PM.