Collection and conversion properties of photovoltaic fluorescent collectors with photonic band stop filters

The thermodynamic limits of photovoltaic solar energy conversion by fluorescent collectors are examined theoretically and experimaentally. The maximum efficiency of a fluorescent collector corresponds to the Shockley-Queisser limit for a non-concentrating solar cell with a single band gap energy. To achieve this efficiency the collector requires a photonic structure at its surface that acts as an omni-directional spectral band stop filter. Such a band stop filter is also required to achieve the thermodynamic light concentration limit in a fluorescent collector. The potential of photonic structures for the efficiency enhancement of idealized and real fluorescent collectors is highlighted. Analysis of a fluorescent collector system ny spatially resolved light induced current measurements and by quantum efficiency analysis shows that the collection efficiency of a real fluorescent collector system increases by up to 30% with the help of a Bragg stack on top of the collector acting as a band stop filter.