Unexplored opportunities for nanostructures in photovoltaics

In previous studies of quantum well photovoltaic (PV) cells important design freedom has not been systematically investigated. We review an experiment by Fox et al. (Appl. Phys. Lett. 63 (1993) 2917) which demonstrates that details of the nanostructure affect the open-circuit voltage, fill factor and the thermodynamic behaviour. The observed features are not understood. Yet, they indicate the promising potential of such nanostructures for PV devices. Light trapping based on diffraction gratings is also mentioned. It allows spectral tuning to the absorption characteristics of the cell and is compatible with very thin nanostructured PV devices.