Multi-Photon Solar Cell

This proposal addresses the attainment of conversion efficiency exceeding 35% in a single-junction solar cell. Non-absorption of long wavelength photons and thermallization of short wavelength photons accounts for the loss of over half of the incident energy in a single junction cell; however, a large fraction of this energy could be captured if the spectrum is first modified by an efficient photonic process that radically changes quantum efficiency. Such technology may offer reduced cost and weight at efficiency equivalent tandem solar cells, and could yield much higher efficiency than conventional flat panel solar cell approaches. In Phase I the feasibility of using implanted rare earth ions for up- and down-conversion of photon energy is investigated. Si solar cells coated with various ion-implanted thin-film host materials are used as test structures to investigate non-radiative energy transfer. In Phase II, development of highly efficiency cells formed from Si and GaAs will be carried out. BENEFIT: The successful development of this technology will provide a new type of solar cell that can be used for both space and terrestrial power systems. Commercial applications include improvement of power-to-weight ratio of satellite power systems. This technology is also applicable to roof top flat panel solar energy systems. In both applications, improved efficiency offers large system cost benefits, as well as increased power output.