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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.

Molybdenum disulfide (MoS 2 ) has shown highly attractive superiority as a platform for sensing. However, DNA physisorption on the surface of MoS 2 was susceptible to nonspecific probe displacement and false-positive signals. To solve these problems, we have developed a novel MoS 2 –aptamer nanosheet biosensor for detecting thrombin using a covalently linked aptamer to the MoS 2 nanosheet. Ten percent Tween 80 was used to prevent thrombin from nonspecific binding and to rapidly form thiol-DNA/gold nanoparticle (AuNP) conjugates. Furthermore, an MoS 2 and exonuclease coassisted signal amplification strategy was developed to improve the detection limit for thrombin. We used the hybridization of the aptamer molecules and the matched strand with a 5′ terminal thiol to immobilize the aptamer molecules on the surface of AuNPs in AuNPs@MoS 2 nanocomposites. Exonuclease digested the single-strand aptamer and released the thrombin, which was then detected in the next recycle. With the coassisted amplification strategy, a 6 fM detection limit was achieved, showing that this method has higher sensitivity than most reported methods for thrombin detection. The results presented in this work show that this method of covalently attaching the aptamer and using the coassisted amplification is a promising technique for the detection of protein in medical diagnostics.