Plasmonic Light-Trapping Concept for Nanoabsorber Photovoltaics

Abstract

Plasmonic nanoparticles were once sought to harness enormous potential for light-trapping in inorganic thin-film photovoltaics. However, the incorporation of such metallic nanostructures near solar cell absorbing layers without inducing overall harm to performance has proven to be a major obstacle. Herein, we demonstrate a solar cell design which integrates a periodic array of plasmonic Ag nanoparticles within the p-i-n structure of a-Ge:H ultrathin optical cavity solar cells. The plasmonic solar cells showed a 33% short-circuit current density increase relative to geometrically identical cells where the Ag nanoparticles were replaced by SiO2. We experimentally mapped the localized surface plasmon excitations on the surface of Ag nanoparticles embedded in the optoelectronic device using electron energy loss spectroscopy and correlated the results to the device performance. Using three-dimensional optical simulations, we further explored the light-trapping mechanisms responsible for the observed performance enhancements. The nanostructured cells produced localized and tunable charge carrier generation enhancements while maintaining the planar geometry of the ultrathin absorbing layer. Therefore, this design concept provides a direct and useful avenue for initial light-trapping efforts in next-generation photovoltaics based on ultrathin nanoabsorbers, such as few layer transition metal dichalcogenides.

Dynamic Imaging of Multiple SERS Hotspots on Single Nanoparticles

“…Surface-enhanced Raman scattering (SERS) is an increase in Raman efficiency due to extremely localized electromagnetic fields at the surface of, for instance, Au and Ag nanoparticles . These fields can be excited using visible radiation and are tightly confined to only certain areas, known as “plasmonic hotspots”. − Molecules in these hotspots experience enhanced excitation and scattering when probed with the proper laser wavelength and/or polarization. , In recent years, there have been several spectroscopic studies of SERS hotspots consisting of either random structures − or nanofabricated plasmonic antennas. − Plasmonic hotspots are widely explored not only for chemical analysis via SERS, but also for particle/molecule trapping, , enhanced photochemistry, − and even nanolithography. , Images of plasmonic hotspots have been obtained with ∼10 nm resolution by near-field scanning optical microscopy − and with higher resolution by scanning (transmission) electron microscopes using electron energy-loss spectroscopy. − However, while many experiments concentrate on the average optical properties (e.g., the extinction spectrum from a nanoparticle suspension or the transmission spectrum from a nanofabricated substrate) to predict SERS performance, fewer experiments directly probe Raman scattering from single nanostructures (e.g., imaging of subnanoparticle interactions ,− ). Moreover, most reports do not completely explore the time evolution or local origin of fluctuations in the SERS signal.…”

Roles of Near and Far Fields in Plasmon-Enhanced Singlet Oxygen Production

“…29 Also, if the plasmonic effect was simply due to the NPs passively scattering the light, higher EF Δ values should have been obtained at longer metal−photosensitizer separation distances [20 and 30 nm (Figure 2c,d)], because these larger NPs still have significant ϕ S (Table S6). Similar conclusions were recently reached by Brolo et al, 40 who showed the improved performance of solar cells using an array of Ag NPs over a similar device but made with an array replaced by SiO 2 NPs, a difference rationalized by the absence of plasmonic light trapping in the latter.…”

Plasmonic Nanostars: Systematic Review of their Synthesis and Applications

“…Thus, many plasmonic nanostructures with different morphologies (Figure ) and unique electronic, optical, and chemical properties have been synthesized and studied. Exploiting their LSPR characteristics, various applications spanning a wide range of technological fields have been explored, developed, and implemented based on plasmonic nanostructures, including photothermal treatment, targeted drug delivery, precision sensing, enhanced imaging, catalysis, , and photovoltaics …”

“…Exploiting their LSPR characteristics, various applications spanning a wide range of technological fields have been explored, developed, and implemented based on plasmonic nanostructures, including photothermal treatment, 2 targeted drug delivery, 5 precision sensing, 6 enhanced imaging, 7 catalysis, 8,9 and photovoltaics. 10 Noble metal nanostars are one of the most recently developed types of plasmonic nanostructures and have drawn significant attention from many different research communities. The remarkable interest in plasmonic nanostars mostly originates from their superior specific surface areas and dominant numbers of plasmonic hotspots compared to those of other plasmonic nanostructures, 12,13 as illustrated in Figure 3.…”