Plasmonics and nanophotonics for photovoltaics

In recent years, there has been rapid development in the field of nanoscale light trapping for solar cells. This has been driven by the decrease in thickness of solar cells in order to reduce materials costs, as well as advances in fabrication technology and computer power for simulating nanoscale structures. Nanoscale light trapping offers the possibility of enhancing absorption beyond the limits achievable with geometrical optics for certain structures. It also allows the optical design to be separated from the electrical design, as for example in plasmonic solar cells. Most importantly, thin-film cell designs will need to incorporate nanophotonic light trapping in order to reach their ultimate efficiency limits. In this article, we review the major types of nanophotonic light trapping, including plasmonic, diffraction gratings, and random scattering surfaces and describe the major advantages and disadvantages of each. In addition, we describe the most important related fabrication and characterization technologies and provide an outlook on future directions in this field.