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The great application potential of photoluminescent silicon nanocrystals, especially in biomedicine, is significantly reduced due to their limited radiative rate. One of the possible ways to overcome this limitation is enhancing the luminescence by localized plasmons of metallic nanostructures. We report an optimized fabrication of gold nanorod – silicon nanocrystal core–shell nanoparticles with the silica shell as a tunable spacer. The unprecedented structural quality and homogeneity of our hybrid nanoparticles allows for detailed analysis of their luminescence. A strong correlation between dark field scattering and luminescence spectra is shown on a single particle level, indicating a dominant role of the longitudinal plasmonic band in luminescence enhancement. The spacer thickness dependence of photoluminescence intensity enhancement is investigated using a combination of experimental measurements and numerical simulations. An optimal separation distance of 5 nm is found, yielding a 7.2× enhancement of the luminescence intensity. This result is mainly attributed to an increased quantum yield resulting from the Purcell enhanced radiative rate in the nanocrystals. The ease of fabrication, low cost, long-term stability and great emission properties of the hybrid nanoparticles make them a great candidate for bio-imaging or even targeted cancer treatment.

Nature Communications 11, 3821 (2020). doi:10.1038/s41467-020-17632-4, The assembly of plasmonic nanoparticles into ordered 2D- and 3D-superlattices could pave the way towards new tailored materials for plasmonic sensing, photocatalysis and manipulation of light on the nanoscale. The properties of such materials strongly depend on their geometry, and accordingly straightforward protocols to obtain precise plasmonic superlattices are highly desirable. Here, we synthesize large areas of crystalline mono-, bi- and multilayers of gold nanoparticles >20 nm with a small number of defects. The superlattices can be described as hexagonal crystals with standard deviations of the lattice parameter below 1%. The periodic arrangement within the superlattices leads to new well-defined collective plasmon-polariton modes. The general level of achieved superlattice quality will be of benefit for a broad range of applications, ranging from fundamental studies of light–matter interaction to optical metamaterials and substrates for surface-enhanced spectroscopies., Published by Nature Publishing Group UK, [London]

Bacteriochlorophyll c (BChl c) is a naturally occurring pigment which, as a monomer, exhibits strong absorption in the red region (600–700 nm), where the dyes used in the most efficient solar cells absorb only weakly. Herein, we investigate the plasmonic enhancement of photoconversion efficiencies in BChl c sensitized solar cells using gold nanoparticles of different morphologies. Using cyclic voltammetry, a favourable band offset (~0.72 eV) between the lowest unoccupied molecular orbital of BChl c and the conduction band edge of titania photoanode was established. Further, gold nanorods with a localized surface plasmon resonance (SPR) frequency overlapping the absorption maxima of BChl c at ~670 nm were used, and compared with gold nanospheres with a SPR maximum in a region (~525 nm) where BChl c has no absorption. Gold nanorod incorporated solar cells displayed the highest photoconversion efficiency with more than 30% increase in photocurrent, compared to devices containing nanospheres and only BChl c. The results are explained using boundary element method simulations, which show a significantly enhanced scattering cross-section and local electric field in the vicinity of gold nanorods compared to the nanospheres. Electrochemical impedance spectroscopy studies indicate reduced charge transport resistance in both gold nanorod and nanosphere incorporated devices.