Optical aspects in photovoltaic energy conversion

The high efficiencies lately achieved with solar cells are partly based on the use of novel light-cell-coupling schemes that are described. From some of these which are not yet used very much, we expect further achievements in the near future.

More specifically, new cell structures that avoid the front metal grid, and micro-concentrators that avoid rejection of light falling on the metal fingers are described. Special attention is paid to the study of the confinement of light inside the solar cells and outside the solar cells in external cavities, presenting here their theoretical limits which are not very well known. New types of external cavity with a large entry aperture are also reviewed as is their use in spectrum-splitting schemes.