In this work, we demonstrate enhanced light harvesting in dye-sensitized solar cells (DSSCs) with gold nanocubes of controlled shape. Silica-coated nanocubes (Au@ SiO 2 nanocubes) embedded in the photoanodes of DSSCs had a power conversion efficiency of 7.8% relative to 5.8% of reference (TiO 2 only) devices, resulting in a 34% improvement in DSSC performance. Photocurrent behavior and incident photon to current efficiency spectra revealed that device performance is controlled by the particle density of Au@SiO 2 nanocubes and monotonically decreases at very high nanocube concentration. Finite difference time domain simulations suggest that, at the 45 nm size regime, the nanocubes predominantly absorb incident light, giving rise to the lightning rod effect, which results in intense electromagnetic fields at the edges and corners. These intense fields increase the plasmonic molecular coupling, amplifying the carrier generation and DSSC efficiency.

Paper-based substrates integrated with plasmonic nanostructures and combined with surface enhanced Raman spectroscopy (SERS) offer a flexible and lightweight platform for the ultrasensitive optical detection of analytes on any surface. Here, we incorporated multibranched gold nanoantennas (MGNs) on inexpensive filter paper to design MGN-paper dipsticks and swabs for SERS mediated sensing of chemicals, proteins, and pesticides adsorbed on fruits. MGNs are anisotropic nanostructures consisting of a core which serves as the antenna and protrusions that serve as emitters redistributing incident light. The nanoantenna effect gives rise to intense electromagnetic fields on the tips of the protrusions that enabled a detection of 100 pM of 1,4-benzenedithiol and 100 fM of human serum albumin labeled with indocyanine green with the MGN-paper dipsticks. Further, MGN-paper swabs enabled the detection of 62.5 pg of solid state 4-aminothiophenol on a planar surface, and 26.3 mg of methyl parathion adsorbed on an apple. Finite difference time domain simulations demonstrated that the nanoantenna effect can be systematically modulated by altering the core-to-protrusion ratio to generate a $65Â enhancement in the electromagnetic fields localized on the protrusions which may ultimately result in sub-femtomolar to zeptomolar detection sensitivities.

Thin-film hydrogenated amorphous silicon (a-Si:H) solar cells that are free-standing over a 2x2 mm area have been fabricated with thicknesses of 150 nm, 100 nm, and 60 nm. Silver nanoparticles (NPs) created on the front and/or back surfaces of the solar cells led to improvement in performance measures such as current density, overall efficiency, and external quantum efficiency. The effect of changing silver nanoparticle size and incident light angle was tested. Finite-Difference Time-Domain simulations are presented as a way to understand the experimental results as well as guide future research efforts.

In this work, we investigate plasmonic enhancement in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester organic photovoltaics (OPVs) by integrating shape- and size-controlled bimetallic gold core–silver shell nanocrystals (Au–Ag NCs) into the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate hole-transport layer. We observed that the best-performing Au–Ag NC-incorporated OPVs improved the power conversion efficiency by 9% via a broadband increase in photocurrent throughout the visible spectrum. Our experimental and computational results suggest that the observed photocurrent enhancement in plasmonic OPVs originates from both enhanced absorption and improved exciton dissociation and charge collection. This is particularly achieved by placing metal NCs near the interface of the active layer and hole-transport layer. The impedance spectroscopy results suggest that Au–Ag NCs reduce recombination and also increase the internal exciton to carrier efficiency by driving the dissociation of bound charge-transfer states to free carriers.

Plasmonic nanoparticles have unique optical properties and these properties are affected by any surrounding structures, or lack thereof. Nanoparticles are often added to a device without fully assessing the effect that each interface will have on the nanoparticle’s response. In this work, we simulate and fabricate devices utilizing hemispherical nanoparticles integrated into the back reflector of an amorphous silicon solar cell. 3D finite difference time domain simulations were used to calculate the optical absorption of a 300nm amorphous silicon layer as a function of the size of the nanoparticles, the distance between the nanoparticles and the active layer, and the distance between the nanoparticles and the mirror. Two transparent conducting oxides, aluminum doped zinc oxide and indium tin oxide, are investigated to determine the importance of the material properties between the nanoparticles and mirror. Silver hemispherical nanoparticles with a diameter of 150nm placed directly on the a-Si:H and a 60nm aluminum doped zinc oxide layer between the nanoparticles and the mirror lead to a maximum absorption increase of 7.2% in the 500nm to 800nm wavelength range. Experimental devices confirmed the trends predicted by theory but did not achieve enhancement, likely due to fabrication challenges. Fabricating a solar cell with the simulated design requires a high quality transparent conductive oxide and high control over the nanoparticle size distribution.