A nanocomposite of metal nanoclusters/OSTE is fabricated through off-stoichiometric thiol-ene polymerization, incorporating adamantanethiol-protected electrum nanoclusters Au_23-xAg_x(SAdm)₁₅ (where x = 7.44) along with the OSTE monomer. During the photopolymerization, there is a transforfation of the precursor nanoclusters and the nanocomposite achieves a maximum photoluminescence quantum yield of ≈73% at 740 nm and 60% at the 850 nm emission peak. The photophysical characteristics of nanocomposite AuAgNCs@OSTE are examined at both ambient and low temperatures, revealing an improved radiative recombination mechanism through the interactions with polymer radicals. This high photoluminescence quantum yield near-infrared-emitting AuAgNCs@OSTE material, distinguished by a larger Stokes shift, is utilized to fabricate luminescent solar concentrators measuring 5 × 5 × 0.13 cm³. Experimental measurements are conducted to determine the absorption coefficient, reabsorption coefficient, absorption cross-section, and volume concentration of the device. Additionally, theoretical evaluations of waveguiding efficiency and power conversion efficiency are performed and compared with quantum dot-based alternatives. The findings indicate that the metal NCs@OSTE nanocomposite has the potential to function as a highly efficient, heavy-metal-free nanophosphor, demonstrating superior overall performance for semi-transparent luminescent solar concentrator devices and being suitable for a broad range of light conversion applications in the NIR spectrum.

Upconversion nanoparticles (UCNPs) have attracted great interest due to their unique properties such as anti-Stokes shift, high biocompatibility, and photostability compared with other fluorophores. Single UCNP-based studies are important for highly sensitive biosensing and bioimaging. To enhance the photoluminescence (PL) intensity of UCNPs, various plasmonic nanostructures have been investigated in addition to engineering the elements and structures of UCNPs themselves. However, it is crucial but challenging to precisely control the position of a single UCNP relative to plasmonic nanostructures. Herein, gold nanorod dimers (GNRDs) are used to enhance the PL intensity of single UCNPs selectively captured in the gaps of GNRDs. The dimensions of GNRDs are designed with the assistance of COMSOL Multiphysics simulation to have a plasmonic resonance peak around the excitation wavelength for the UCNPs. After lithography-based fabrication of GNRDs and surface passivation, electron-beam induced deposition is used to selectively create carbon nanodomains (CNDs) in the gaps of GNRDs. The CNDs capture UCNPs by benefiting from the strong affinity between streptavidin and biotin. About 12% of the CNDs capture single UCNPs. Photoluminescence imaging shows an overall intensity enhancement by threefold for single UCNPs by GNRDs of 100 nm gap at 4 × 10 6 W / cm 2 power density. This study shows a promising route for single UCNP-based studies, especially when it is needed to control the position of single UCNPs.

We demonstrate that dielectric Mie scatterers, in the form of silicon nanoparticles (SiNPs), can enhance both the performance and esthetics of semitransparent photovoltaic devices. Unlike plasmonic metal counterparts, dielectric SiNPs exhibit lossless, narrow-band, spectral, and spatially tunable scattering in the visible spectral range. Their effect on a luminescent solar concentrator (LSC) with high visible light transparency is analyzed both theoretically and experimentally as a model system. By selectively reflecting a specific spectral band, SiNPs increase the optical path length of solar photons within the active layer, leading to improved absorption and hence device efficiency. Simultaneously, this light management strategy ensures transmitted color neutrality, an important requirement for wider acceptance of semitransparent photovoltaics. Numerical simulations show that in the regime of individual SiNPs with diameters around 160 nm, a submonolayer surface coverage of ∼10% is sufficient to achieve color neutrality, at the same time enhancing photocurrent by 10–15% for an LSC device. Experimentally, such a dispersed SiNP layer on an LSC substrate is realized by depositing NPs with the surface capped by a sacrificial polymer shell. Subsequent etching of the shell by oxygen plasma leads to an LSC device with a functional selective scattering layer in line with theoretical predictions.

High-pressure water vapor annealing (HWA) was recently demonstrated as a method that can substantially improve the photoluminescence quantum yield (PLQY) of silicon quantum dots (Si QDs) with the oxide shell. In this Letter, the mechanism of this enhancement is studied optically on a single-dot level. HWA treatment is performed on Si QDs formed on a silicon-on-insulator wafer, and their photoluminescence (PL) properties were examined before and after the treatment. Our experiments show a 2.5 time enhancement in the average blinking duty cycle of Si QDs after 2.6 MPa HWA treatment without changing the average ON-state PL intensity. This observation proves the carrier trapping process is suppressed on the HWA-built Si/SiO2 interface. We also discussed the mechanism behind the PLQY enhancement of HWA-treated Si QDs by comparing single-dot-level data to reported ensemble PL Si QDs results. HWA treatment is found to mainly brighten "grey" (not 100% efficient) QDs, a mechanism different from changing dark (non-emitting) to bright (100% efficient) Si QDs by ligand passivation.

Fluorescence-based single-molecule detection has been widely investigated and applied in biosensing and bioimaging due to its ultrahigh sensitivity and specificity. However, bulky and expensive commercial fluorescence microscopes are usually required. The Stokes shift property of most commonly used fluorophores requires optical sets such as dichroic mirrors and specific filters in the optical pathway before a photodetector to eliminate excitation and scattering lights from the fluorescence signals. The fluorescence signal collected by an objective is further unavoidably attenuated, and the optical resolution is diffraction-limited. Herein, a proof of concept of a lab-on-a-chip compatible molecular sensor is shown by integrating upconversion nanoparticles (UCNPs) and amorphous hydrogen-doped InGaZnO (InGaZnO:H) thin-film phototransistor (IGZO:H TFTs) aiming to alleviate those issues. Upon illumination with a 980 nm infrared light, the phototransistor shows no photocurrent without UCNPs but yields a high photocurrent with UV-visible fluorescent light emitted from the UCNPs. The molecular detection is enabled by further involving the Förster resonance energy transfer (FRET) mechanism, with the UCNPs as donors. The photocurrent falls back to its original low level when biotinylated gold nanoparticles are added to selectively bind and quench the UCNPs via biotin-streptavidin coupling. Each UCNP shows an estimated photocurrent-to-dark current ratio of 10³ and each biotinylated gold nanoparticle causes at least 1 order of magnitude decrease of the photocurrent. Our integrated setup presents a promising platform for further development toward an optoelectronic biosensor capable of single-molecule detection.

This Letter introduces an analytical approach to estimate the waveguiding efficiency of large-area luminescent solar concentrators (LSCs), where the edges are covered by a var-ied number of mirrors and solar cells. The model provides physically relevant description in the whole range of optical (absorption, scattering) and geometrical (size) parameters of rectangular LSCs. A 19 x 19 cm2 silicon quantum dot -based LSC has been fabricated to verify the theory. Within an experimental error, the predicted waveguiding efficiency matched well the measured one. A critical LSC size, beyond which a part of the device turns inactive, has been deter-mined as N/& alpha; for N attached solar cells (one or two) and LSC material absorption coefficient & alpha;. This model provides a straightforward waveguiding analysis tool for large-area LSCs with different structural parameters relevant for both high concentration ratio and glazing applications.

Dielectric breakdown etching is a well-known method of making nanopores on thin (similar to 50 nm) dielectric membranes. However, voltage driven translocation of biomolecules through such nanopores becomes extremely fast. For improved detection, for instance by the current blockage, a high-aspect-ratio nanopore could be beneficial for slowing down the translocation. High-aspect-ratio nanopore on silicon fabrication requires a well-controlled process and is dependent on specific crystal orientation, dopant type and resistivity of substrate. Therefore, an optimized method of processing high-aspect-ratio nanopores is necessary considering the advantage of a silicon membrane being able to be integrated with standard CMOS processing. Here, we present an optimized fabrication method for mass-producing a single and an array of nanopores on a thick (2 mu m) silicon device layer based on a silicon-on-insulator (SOI) wafer. A method of temporal voltage variation is exploited to optimize the etching parameters for the nanopore formation during electrochemical breakdown etching, diameters of nanopores around 12 nm have been achieved. Besides, the correlation between the parameters of etching and nanopore diameter is deduced. The processed high-aspect-ratio nanopore enables applications in single-molecule sensing such as DNA, exosomes, viruses, and protein markers. The developed process is inexpensive, fast and can be batch fabricated.