Abstract
A technique of obtaining plexitonic structures based on Ag2S quantum dots passivated with l-cysteine (Ag2S/l-Cys QDs) in the presence of Au nanorods passivated with cetyltrimethylammonium bromide molecules (Au/CTAB NRs) with controlled luminescence properties has been developed. The structural and luminescence properties of Ag2S/l-Cys QDs with Au/CTAB NRs are studied. 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 7.2 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. In the case of formation [Ag2S QD/l-Cys]/[polyDADMAC]/[Au/CTAB NRs] a transformation of shallow trap state structure was established using the thermostimulated luminescence method.
Highlights
A technique of obtaining plexitonic structures based on Ag2S quantum dots passivated with L-cysteine (Ag2S/L-Cys QDs) in the presence of Au nanorods passivated with cetyltrimethylammonium bromide molecules (Au/CTAB NRs) with controlled luminescence properties has been developed
Analysis of the transmission electron microscope (TEM) images of Ag2S/L-Cys QDs revealed the formation of individual nanocrystals with an average size of 2.1 Æ 0.5 nm and size dispersion of $30%, which is due to the chosen approach of colloidal synthesis in an aqueous solution (Fig. 2a)
According to high-resolution TEM (HR-TEM) and TEM data (Fig. 2c and c0), the approach used to obtain the mixtures of Ag2S/L-Cys QDs and Au NRs ensures compatibility of the components and formation of hybrid structures with good reproducibility
Summary
The formation of hybrid nanostructures based on semiconductor colloidal quantum dots (QDs) with unique photoluminescence properties, which are uncharacteristic of individual components, is relevant for photonic applications, such as optoelectronics, photovoltaics, bioimaging, and luminescent sensors.[1,2,3,4,5,6,7,8,9] The luminescence properties of the hybrid nanostructures, such as high luminescence quantum yield and photostability, as well as the radiative lifetime, are key parameters that determine the area and potential for these applications.[1,2,3,4,5,6,7,8,9]. Note that for metal-conducting structures containing Ag2S QDs, plexcitonic effects have not yet been considered in detail with regard to the luminescence properties of such complex systems
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