Classifiying advanced concepts to assess device requirements for high efficiency solar cells

The efficiency of terrestrial solar energy conversion is fundamentally limited by the Landsberg limit of 93%. Single junction solar cells can, however, reach only about a third of this efficiency, a limitation first formulated by Shockley and Queisser [1] . Many concepts have been proposed to overcome this Shockley-Queisser (SQ) limit for single junction solar cells. In this contribution, we are going to explore the classification of these concepts according to the processes that occur in them and explain how this affects model-building for these devices and the requirements they have to fulfil.