4–7 This phenomenon seems to break the well-known Kasha’s rule however, the mechanism is unclear. Several groups have reported this excitation wavelength dependence at the ensemble level that the PL decay of QDs near plasmonic nanostructures tends to be faster when excited spectrally close to the LSPR peak. 3 Changing the excitation wavelength also has an impact on the PL decay of QDs near plasmonic nanostructures. For example, it was found that when the excitation wavelength overlaps with the LSPR peak of gold (Au) NPs, the statistics of the photons emitted from nearby single QDs could switch from anti-bunched to bunched. Alternatively, when the geometry and composition of a plasmonic metal NP-QD hybrid system are fixed, changing the excitation wavelength provides a simple but effective strategy to modulate the photophysical characteristics of QDs since the plasmonic effect is highly excitation wavelength-dependent. Plasmonic modulation of QD PL is often realized via the geometry and composition of the hybrid structure, which requires much synthetic effort. Thus, the overall effect of plasmonic NPs on PL intensity and lifetime of QDs is a result of multiple factors. Moreover, metal NPs could also accept energy or charges from the excited QDs, providing additional non-radiative recombination pathways to quench the photoluminescence (PL) of QDs. At the meantime, a plasmonic metal NP could also accelerate the radiative excitonic recombination of nearby QDs through Purcell effect. 2 The created electric field near a metal NP will then enhance the absorption of fluorophores, such as QDs in the vicinity. 1 Plasmonic metal NPs are known for localized surface plasmon resonance (LSPR) that describes the collective oscillation of the surface conduction electrons upon electromagnetic excitation. Based on transient absorption spectroscopy measurements, we also analyse the evolution of gain with the proportion of selenium in the core.Hybrid nanosystems consisting of plasmonic metal nanoparticles (NPs) and quantum dots (QDs) have been of tremendous interest for QD-related optical and optoelectronic applications, largely because plasmonic NPs offer the flexibility of modulating the photophysical properties of nearby fluorescent QDs for desired applications. We study CdSe(1-x)Sx\ZnS\ZnS QDs with various compositions of the alloyed core and we show that, by changing the ratio between sulfur and selenium, one can shift continuously from type I to type II. Here, we present an original method to finely tune the band structure of visible emitting core\shell QDs between type I and type II. On the contrary, in type I QDs, such as CdSe\ZnSe, both charge carriers are strongly confined in the core, what results in high emission quantum yield and single photon emitter behaviour. In type II QDs, such as CdS/ZnSe, one type of charge carrier is confined in the core and the other in the shell, what allows single exciton gain. Moreover, the band structure of core shell QDs give rise to interesting features. In that view, core-shell quantum dots (QDs) show unique properties: their emission wavelength can be tuned, they present high quantum yield and their integration in photonic devices is based on classical fabrication process. The integration of reliable light sources would make these devices more efficient, more robust and would allow the integration of active components. Nowadays, light is in most cases generated outside of the photonic device, coupled with it through optical fibers. Center for nano- and biophotonics (NB-Photonics)Ībstract Integrated optics have a wide range of applications in telecommunications, information treatment and lab-on-chip analysis.Department of Inorganic and physical chemistry (ceased 1-1-2018).
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