Rafael Kleiman
Professor, Engineering Physics

My research program is a multi-faceted effort to develop high efficiency and low cost photovoltaic devices. Theoretical efficiencies for single junction devices are limited to ~30% at 1 sun, based upon standard assumptions for the conversion of light to electron-hole pairs in a semiconductor. A proven route to higher efficiencies is via multijunction solar cell technology in which monolithic series-connected solar cells are fabricated, with each cell optimized for a different part of the solar spectrum. Current multijunction devices are expensive relative to single junction devices due to the high cost of their exotic substrates. We are developing a new generation of multijunction solar cells, based upon the growth of III-V semiconductors on high quality ubiquitous Silicon substrates to achieve high efficiencies, providing a significantly lower cost per installed Watt. We are also developing other third generation devices, based upon novel materials, concepts and architectures.