Spectral characteristics of nanometric absorber: a simple strategy to develop silicon nanostructures for efficient solar energy harvesting

Solar cells utilise a small portion of the solar spectrum depending on the technology used while solar radiation, being full of UV-VIS-IR wavelengths, does not leave absorbing and other layers unaffected. Only the photon energy that matches the absorbing layer contributes to effective power generation of solar cells. Higher and lower energy wavelengths induce thermalisation and absorption losses, which in turn introduce several consequences including heating and degradation in the cell level. Therefore, wavelength-sensitive engineered absorbing layers such as nanometric absorber-based solar cells hold huge potential. In this work, we have investigated and simulated four deterministic characteristics, viz. absorption depth profile; electromagnetic field; Poynting vector and exciton generation rate distribution at different incidents for silicon nanowire (Si-NW) systems. Flat silicon and Si-NW were considered as examples along with a comparative outlook. Such predictive studies facilitate the choice of technology and how to improve the cell efficiency using light-trapping techniques. Preliminary work has shown a simple strategy to achieve nanometric absorption using recent inventions granted to the Center of Research Excellence in Renewable Energy (CoRERE) at King Fahd University of Petroleum and Minerals (KFUPM). As-grown Si-NWs with coverage, ca. 6.5×10⁸/cm² were further characterised through scanning electron microscope. Such correlated demonstration as investigated in this work will open new avenues and possibilities to improve current nanowires-based optoelectronic devices, particularly thin film solar cells.