Hot-Electron Generators Based on Plasmonic Inverted-Pyramid Arrays for Solar-Energy Harvesting

In any solar cell, the exploitable spectral range of sunlight is limited by the band gap of the active photovoltaic material, which in the case of silicon is 1.1 eV (roughly 1100 nm). Thus, nearly half of the solar spectrum remains unabsorbed, namely, the near infrared (NIR) part. To alleviate this situation, a common alternative to photoelectric conversion relies on the mechanism of plasmon-enhanced internal photoemission of hot electrons at metal/semiconductor heterostructures. Photons with energies below the gap of the semiconductor are absorbed by the metal, launching surface plasmons, which, upon relaxation, produce a photocurrent of hot carriers into the semiconductor.