Abstract: A multi-junction power converter system illuminated by an incident light source includes a multi-layer stack having a plurality of junctions defined by materials having different bandgaps, with an upper junction having a higher bandgap, and junctions therebelow having smaller bandgaps. The upper junction absorbs more of the incident light, whereas lower junctions successively absorb less of the remaining incident light. The junctions below the upper junction are supplied with additional illumination that has been reemitted from previous cells due to photon recycling. Related devices and methods of operation are also discussed.

Abstract: An optical element for use in a concentrating photovoltaic system for converting incident solar radiation to electrical energy. The optical element may include an entry aperture for receiving light beams from a primary focusing element, and an exit aperture for transmitting light beams to a solar cell. The optical element may also include an intermediate section whereby at least some of the light beams reflect off the intermediate section and are transmitted to the solar cell. This region may be composed of a layered structure with a first material layer having a first optical characteristic, and a second material layer having a second optical characteristic. The material composition and thickness of the layers may be adapted so that the reflectivity of the light beams off the surfaces and transmitted to the solar cell optimizes the aggregate irradiance on the surface of the solar cell over the incident solar spectrum.