Plasmonic Light Trapping in an Ultrathin Photovoltaic Layer with Film-Coupled Metamaterial Structures

A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced in the film-coupled metamaterial structure, resulting in significant enhancement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency

Salinity tolerance traits in three grass species:Potential selection criteria for varieties for future sustainable farming

In this thesis, we tested Puccinellia maritima as a model forage grasses under saline conditions in comparison with two other grass species Festuca rubra and Lolium perenne. We compared different cultivation substrates under salt treatment with harvest for mimic cutting regime. The results demonstrate that, under simulated grazing or cutting conditions, P. maritima is the superior salinity tolerant specie, under even high salt conditions. During short term and long-term salinity, P. maritima maintain a high photosynthetic electron transport rate and maximum photosynthetic efficiency (Fv/Fm). The root system architecture (RSA) of P. maritima responds very differently from the other two. P. maritima increases the seminal root length under moderate salinity. The root surface ion flux under salt and salt addition varies in ion transportation. A moderate salinity addition (50 mM NaCl) fails to induce P. maritima loss of H and K. The higher salt of 100 mM induces quite less K flux in P. maritima than L. perenne and F. rubra, and the salt shock recovered fast within 5 min to a stable status. Meanwhile, we isolated endophytes from salt marsh F. rubra and inserted to the commercial F. rubra, leading to shoot growth and decreasing of the K+ loss. This experiment highlights that not only the halophyte plant itself but also endophytic fungi are important. In breeding programs, these different traits could be exploited, within subspecies as they are examples associated with (temporary) reduced above ground productivity